BOULDER - August 1 - TECHtionary.com today announced "SIP Planning Guide 2.5," a significant expansion of what's been called the "quintessential" planning guide for SIP-VoIP, UC-Unified Communications, Microsoft OCS-Office Communications Server & Response Point and IPT-Internet Protocol Telephony networks. SIP Planning Guide 2.5 provides the means for customers who are planning, implementing and expanding their communications networks to "get SIP smart" with guidance, ideas and tools. With more than one hundred new concepts for review, SIP Planning Guide 2.5 is vital to anyone doing UC/VoIP/SIP/IPT for network solutions and premise-based implementations.

Some of the key highlights in SIP Planning Guide 2.5:
- VLPS-Virtual Private LAN Service with MPLS
- Privacy-Security Lifecycle Management - Authors - Actualizers - Auditors - Analyzers
- PLC-Packet Loss Concealment - zero Insertion, wave-form substitution, etc.
- SIGTRAN (Signaling Transport)
- SCTP-Stream Control Transmission Protocol
- New options and new roles for Media Gateways replacing PBXs
- Expanded details on SBC-Session Border Controllers
- 50 point security checklist
- More than 30 solutions to common problems and troubleshooting guide
- Improved section on QoS and RTCP-XR-MRB
- Indepth explanations of complex problems such as echo, crosstalk and asynchronous transcoding
- "Vo-eye-P" packet test
- Many other improvements, solutions, ideas and technology.

"SIP Planning Guide 2.5 continues to improve in nearly every aspect of UC-Unified Communications, VoIP-SIP, OCS and IPT. This course is now even more vital to every organization as VoIP/SIP is new and new approaches to planning and managing are important to understand how. Coupled with the new improved solutions-answers, privacy/security section, troubleshooting guide and QoS primer, SIP Planning Guide 2.0c courses are without peer from any source." noted Paul C. Daubitz - President - ATI-TeleManagement (http://www.ati-telemgt.com a professional management consultancy).

"SIP Planning Guide 2.5 takes our SIP/OCS courses to the critically important next level," noted Tom Cross TECHtionary CEO. "SIP is a complex process because SIP is not just a single location service but one that encompasses nearly all aspects of business communications and computing," Cross added.

SIP Planning Guide 2.5 is available in the onsite and online courses. The online version is $199 per person or four (4) for $499. Add-On OCS Module - there is a special OCS-101 Office Communications Server module for $99 per user or less with discounts. Special SIP Forum Member and Microsoft Partner price is $99 per user.

For a complete detailed course outline go to: http://www.techtionary.com/sip/planning-guide/

Courses are also available from TelecomWebU at: http://www.telecomweb.com/

For more information go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.

Related Entries
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• New Public Seminar Course Schedule for New CompTIA Security+ - Jun 15, 2008

BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program

Boulder: Boulder Valley School District's Lifelong Learning Program proudly announces innovative online courses designed for high school students and adult learners. As technology continues to evolve at break-neck speed, it has become increasingly critical for students of all ages to stay ahead of these advances. The new Lifelong Learning "Internet Studies" Program online courses are the perfect Web-based solution. According to Shere Holleman, BVSD/LLL, "Our classes reach over 4500 students each year and most of them take place in school district facilities. However, in today's 'split-second society' there is an urgent need to provide flexible learning options where students can attend classes anytime, 7 days a week, 24 hours a day from anywhere. In addition, Internet Studies can help keep students on the cutting edge of technology so they can compete in the global economy."
Students and adults alike are faced with an increasingly competitive work environment. BVSD's Lifelong Learning Internet Studies program helps address this problem by allowing anyone to get answers to many technical questions through online learning and this partnership with TECHtionary.com.
Tom Cross, TECHtionary.com and Internet Studies developer/instructor, explains, "New technology continues to expand more rapidly than ever, as WiFi, WiMax, SIP, Voice over IP, Metro Ethernet, storage, web conferencing and other emerging technologies become more widely accepted. To offer a truly innovative education, students of all ages need to know all about today's technology and be informed on what's being developed for tomorrow. With Internet Studies online courses, anyone can become a credible expert."
Online courses are available for $155 each. Course titles include:

- Internet Studies 101: Communications Technology Manager
Introduction to the Fundamentals - Course #200037

- Internet Studies 201: Wireless Technology Manager - Course #200038
Job Training and Implementation of WiFi, WiMax, Cellular and IMS

- Internet Studies 201 - VBE - VoIP Business Executive - Course #200047
Channel Provider & Partner Business Sales & Technical Strategies for VoIP-SIP

- Internet Studies 201 - STE - SIP Technology Business Executive - Course #200048
SIP ESSENTIALS - An Executive Guide to SIP-Session Initiation Protocol

- Internet Studies 301: Advanced Data Networking - Course #200040

Preparation for industry-wide Cisco, Microsoft, Avaya, Comptia and other certifications
If a student takes all three courses and passes multiple choice exams for each course receiving more than 80% correct, she/he will receive a BVSD/Lifelong Learning Education Certificate.
For more information and to register, go to www.bvsd.org/lll and Click on Courses, then Computers, then scroll down to Internet Studies.
http://bouldervalley.augusoft.net/index.cfm?fuseaction=1011&CategoryID=2&SubCategoryID=5
Additional courses will be forthcoming in advanced VoIP-Voice Over Internet Protocol telephony, Microsoft's OCS-Office Communications Server, SIP-Session Initiation Protocol and others. These courses are available for corporate onsite, online, webseminar or other delivery formats.

About Lifelong Learning:
Lifelong Learning is part of the Community School Program and is a self-supporting entity of the Boulder Valley School District. Since its inception in 1984, the program has been committed to providing affordable, locally-based educational experiences that enrich the entire community.

Related Entries
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• Increased SIP Performance with Stream Control Transmission Protocol - Jul 17, 2008

The animated tutorial can be found here:
tcp-sctp.swf

For SIP-Session Initiation Protocol, the advantages of SCTP are: - Increased congestion control via larger congestion window - Multi-streaming - Multi-homing
In the animated tutorial there is a chart with many of the other advantages and differences between TCP and UDP. SCTP-Stream Control Transmission Protocol was created to overcome TCP-Transmission Control Protocol limitations with respect of TCP "sawtoothing" (send-wait-send) transmission on voice signals. SCTP also adds multi-homing where this is more than one path between hosts for resilience (reliability).

In SCTP data content is organized into "chunks" overcoming TCP limitations of a single byte stream, HOL-Head-Of-Line problems (explained next) and DOS-Denial-Of-Service attacks. Shown in the animated tutorial, HOL-Head-Of-Line blocking is caused when there are many discrete (separate) transactions and the during the connection setup subsequent (following) setup messages are held until the lost message is retransmitted (re-sent - Fast Transmit) and understood (received and accepted). That is, all messages are not passed to Upper Layer Applications until the previous messages sent prior (ahead-of-the-line) are accepted. This may not be a problem in many applications but can be in telephony and streaming.

SCTP adds other features such as multi-streaming which supports independent transport and delivery of multiple streams between two communications host servers (shown here). In addition, SCTP adds multi-homing (via different AS-Autonomous Systems) where there are multiple paths between hosts for resilience (reliability). Shown here are the four types of pathways that are supported by SCTP and the failover/resiliency that occurs if there is a loss of connection. Multihoming allows each of the two endpoints during an SCTP connection to setup and specify multiple IP address endpoints. With multiple interfaces, this allows data to be automatically redirected to alternate IP addresses when failures occur. A feature not found in TCP is that redirection can occur without knowledge of or involvement with the ULP-Upper Layer Protocol application. TCP connections are also bound to a single interface.

SIGTRAN (Signaling Transport) is IETF's working group related to the transmission of packet-based signaling over IP networks. SCTP is critical to bridging SS7 to SIP protocol. In other words how do you transport ISUP-ISDN User Part signaling through MTUA-MTP(Message Transport Part) level 3 User Adaption Layer. One of the purposes of this tutorial is to show how SCTP provides support for SS7-Signaling System 7. MTPUA-MTP level 3 User Adaptation Layer as show here along with M2UA-MTP level 2 and M2PA-MTP level 2 Peer-to-peer Adaptation Layer are transported via SCTP-IP.
While it is way beyond the scope of this presentation to explore all the security ramifications of SCTP because of its multihoming and multistreaming features offer additional layers of protection from against blind DOS-Denial Of Service attacks such as flooding, masquerading, and improper port access. In addition, the SIGTRAN specification in conjunction with SCTP requires the use of security schemes IP Sec-IP Security, TLS-Transport Layer Security and IKE- IKE-Internet Key Exchange or SKIP-Simple Key exchange. IP Sec is a Layer 3 Network service. In comparison, SSL-Secure Sockets Layer is a Layer 7 Application service which uses digital certificate to provide a means of secure authentication/authorization. In IP Sec, there are two types. In IP Sec TRANSPORT MODE, only the user data is encrypted.
In IP Sec TUNNEL MODE, both the user data and the IP Packet are encrypted.
IKE-Internet Key Exchange or SKIP-Simple Key exchange IP support many different encryption standards such as Diffie-Hellman key exchange, public key cryptography, DES-Data Encryption Standard and 3DES-triple DES, digital certificates and others. Please refer to www.ietf.org for more.

Shown in the animated tutorial - TCP-Transmission Control Protocol relies on a sliding-window (slide the window to the receiver with data and then wait for the receiver to slide the window back ACKnowledging receipt of data) approach for congestion control. TCP connections provide end-to-end flow control to limit the number of packets in the network. The flow control is enforced by two windows - Sender-CWMD-Congestion WiNDow and receiver RCVWND-ReCeiVer WiNDow enforced by the Receiver as measure of its buffering capacity. The CWND is maintained by the Sender as means and measure of the capacity of the network. The Sender sends data packets one window at a time, and cannot send more than the minimum of RCVWND and CWND into the network.

SS-Slow Start is a control method of managing TCP error and congestion control. The CWND-Congestion WiNDow is doubled every round trip time during the Slow Start phase. The Slow Start phase continues until CWND reaches SSTHRESH-Slow Start THRESHold (generally set to 64K bytes) and then the congestion avoidance phase begins. During the congestion avoidance phase, the Sender increases it's CWND (by 1/CWND) every time a segment is acknowledged. The Slow Start and the congestion avoidance phases correspond to an exponential increase and a linear increase of the congestion window every round trip time respectively.

In the event of a failure, RTO-Retransmission TimeOut also called Fast Retransmit provides if the TCP Receiver receives a packet out-of-order to respond to the Sender with a duplicate ACKnowledgement. In addition, Fast Recovery allows the Sender to increase the CWND to allow more packets to be sent. Fast Retransmit is designed to improve recovery by avoiding SS-Slow Start, keep "pipes" (bandwidth) in maximum use and recover from packet losse(s) as fast as possible.

Fast Recovery (deflate/reduce CWND) is also a means of SACK-Selectively transmit ACKnowledgement based on Receiver response. Inflate the CWND-Congestion WiNDow to allow more packets to enter the network during Fast Retransmit process.

Called Extended Entry, the TCP-Transmission Control Protocol or UDP-User Datagram Protocol Port number is added to the router translation table. Extended Entry addressing could allow up to 4,000 different hosts to share the same IP addresses by using different TCP-UDP Port numbers.

Overloading (over-writing) also known as PAT-Port Address Translation is the process of re-using the same IP address by internal users to access different internet hosts using Extended Entries. Distant hosts think they are communicating with a single IP address. TCP Load Distribution translates certain global (legal) into valid internal IP addresses destined for more than one node.
This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm
This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.

Related Entries
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008

This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.

Related Entries

The animated "pictutorial" is available at http://www.techtionary.com

Resistance to Wind Power

In other words, wind power is great where there is wind and consumers nearby. However, if there is wind power in Wyoming, there is little power in Chicago due to the amount of electrical resistance. Understand resistance is critical to understanding power generation and consumption.

The output of the typical electrical power generator is 13 KV-KiloVolts. The voltage is increased to 115 KV and then to 230 KV for metropolitan or long distance transmission. At the destination, the power is reduced to 115K and then to 13 KV and then to 220 Volts for household use. Why increase the voltage? To reduce power loss due to resistance: P = IV = I²R. That is, power loss is due to wire resistance increases as the square of the current as well as decreases as the square of the voltage. The higher the voltage, the lower the current and the lower the resistance or power lost during transmission. That is, the greater the distance, the higher the resistance and the lower the output at the distant end.

Why Resistance Kills Wind Power

Electrical power loss due to wire resistance (lost as heat) increases as the square of the current or P = I²R and therefore decreases as the square of the voltage. This relationship is one of Ohm's based on E=IR or voltage equals current multiplied by resistance. Resistance is the measure of electrical current when voltage is transmitted per volt applied. That is, the amount of V-Voltage divided by the current I is the Resistance. R-Resistance is defined by the formula R = V/I. Resistance is measured in units called ohms, represented by the Greek letter omega. Electrical current or amperes (amps) is the flow of electrical charge. However, the charge encounters friction called resistance. Copper, gold, aluminum and other metals have low resistance (without loss of electrical power) to electrical current and are called good conductors. Glass, ceramic, wood and the earth have a high resistance (impede the flow of current) and are called poor conductors. Superconductors like very cold niobium-tin, are special substances that allow current to flow with essentially zero loss. Semiconductors, like silicon, can be either good or poor conductors depending on electrical charges applied to their surface.

Tutorial on Wind Power Generators

According to GE Energy, "wind is the fastest growing energy source with an AGR-Average Growth Rate of 35.7% over the past five years. Globally, installed wind capacity increased to 3,200 megawatts during 2002. In Ireland, wind generates 175 megawatts. In regions of Denmark, Germany and Spain up to 25% of the electricity is generated by wind. Forecasts for electricity wind generation are projected to exceed 83,000 megawatts by 2007."

The number of wind blades is generally 2 or 3 with rotor diameters from 84 to 104 meters (341 feet) and rotor speed up to 18 RPM-Revolutions per minute. Propeller pitch (blade angle) control for each blade provides for improved performance. Each blade and all internal systems have lightning surge protection. Automatic Yaw control (rotation or swivel) of the Nacelle is controlled by the wind direction sensor.

Power output is based on wind flow. Beginning with wind speed as little as 3.5 meters per second (~8 MPH-Miles Per Hour) and reaching maximum output of 24-3600 KW-Kilowatts at 14-16 MPS-Meters Per Second (~20 MPH). In technical language, the generator Cut-in (minimum wind speed to generate electricity) wind speed is 3.5 MPS and Cut-Out (the wind speed at which the turbine is shut down to avoid structural overload) wind speed is 25 MPS. The generator also has a hydraulic breaking system for failsafe protection.

The tower and the Nacelle (generator and control housing) are constructed of tubular steel. One of the functions of the propeller pitch control (shown here) is change the angle of interface to the wind to maintain constant output even though wind speeds vary. A three-step planetary gear system is used to reduce excessive torque excursions (differences) to maintain constant speed and electrical output. The input variable for the pitch controller is the rotor speed. The higher the rotor speed, the more the blades are turned out of the wind.

In general, fixed speed turbines use stall condition for technical reasons, while variable speed turbines are usually equipped with pitch control to manage stall (reduced wing air flow). In newer systems it is called AS-Active-Stall. This is similar to normal stall power limitation except that the whole blade can be rotated backwards (in the opposite direction as is the case with pitch control) by a few (3-5) degrees at the nominal speed range in order to give better rotor control. The result is known as the 'deep stall' effect, which leads to the power curve bending sharply to a horizontal output line at nominal power and keeping this constant value for all wind speeds between nominal and cut-out.

The Nacelle housing contains the AC-Alternating Current three-phase generator with an IGBT-Insolated Gate Bipolar Transistor converter (AC-DC-AC converter). Most new wind generators use Low Voltage Ride-Through Capability designed to protect interfaces from the electrical from voltage "trips" - faults or drops out resulting from disturbances in the high-voltage electrical grid. The Nacelle also contains control panels, ventilation and a gantry crane for maintenance.

Because of the variability of wind, conventional electric generators are not always desirable. Here are some but certainly not all of the key generator types used in wind energy: CT/CS = Constant (fixed) Turbine speed - Classic Stall (fixed blade angle) CT/AS = Constant (fixed) Turbine speed - Active Stall (negative variable blade angle, 3-5 degrees) VTDI = Variable Turbine speed and pitch - Doubly-fed Induction generator VTDD = Variable Turbine speed, Direct Drive synchronous generator VTSGP = Variable Speed/pitch combined with (brushless) Synchronous Generator VT/AGP = Variable Speed /pitch combined with Asynchronous Generator (100% current via converter) CT/AGP = combination of fixed speed /pitch with directly connected to asynchronous generator. SVT/OSP = semi-variable speed/pitch combined with (maximum +10% variation in nominal speed)

A CT-Constant (fixed) Turbine speed turbine consists of a rotor and a squirrel cage induction generator connected via a gearbox. The generator stator winding is connected directly to the electrical power grid. The generator slip varies with the generated power so the speed is not always constant. If wind flow drops a squirrel cage generator draws (receives) reactive power from the grid. In order to compensate for the reactive mode, electrical storage capacitors are used to send power to the grid.

In a VT-Variable speed Turbine with Doubly-fed (double feeds to the grid) induction generator, the converter feeds the rotor winding, while the stator winding is connected directly to the grid. The electrical rotor frequency can be varied by this converter which can change the mechanical and electrical frequency and making variable speed operation possible.

In a VT-Variable speed Turbine with DD-Direct Drive Synchronous generator is managed without a gearbox by the electronic converter to provide for variable speed operation. The advantages of variable speed turbines are greater energy with lower wind speeds with active/reactive power is controlled by the converter.

The function of the Converter is to balance electrical output from the wind generator to the demands/needs of the electrical power grid. By changing the pitch of the blades and through AC-DC-AC inverter technology such as an IGBT-Insolated Gate Bipolar Transistor converter (AC-DC-AC converter) power regulation is controlled.

AC-Alternating Current generated by the wind generator is stepped up (increased) to 115/230,000 volts for transmission to a neighborhood substation/switching yard. Voltage is then Stepped Down (voltage decreased) by an underground (shown here) or overhead "can" transformer from 13,200 to 7,600 volts to house/business distribution voltage of 277/480 or 110/220 volts AC for use in lights, appliances and other devices.

Related Entries

Related Entries

Comments on this Entry:

(iphoneuser on Jul 12, 2008 8:31 PM) So I don't get it. You must be the only guy in the world who didn't sync and backup his iphone before updating. Granted the activation servers were down and updates weren't working for a while, but I guess you got what you deserve if you didn't even bother to sync before upgrading. If you *did* sync first and just listened to at&t drones that they couldn't help you fix your phone then look in library > itunes > backups or similar and see if you have a backup. If you do, just restore your iphone to the previous version and restore your backup. then upgrade to 2.0 again and you will be fine with all your data and settings again. Tom wrote: I was kinda busy and have done this many times before without issue. And, yes, it all came back except for the vmail just fine. I had come to expect Apple knew what they are doing and now realize they don't.

(Anonymous on Jul 28, 2008 1:19 PM) I would like to tell my AT&T/Apple iPhone story.....I had one in my hand(s) but couldn't buy it. I was so close. I waited -- first for the new one....even though I needed a phone 3 months ago. I waited for the frenzy to subside a bit, so I wasn't waiting hours in line. I was there - at the front - inches away from purchasing, having, using a coveed iPhone. helpful Apple person: "hi - who is your current cell phone provider? AT&T. Phone number?.....ya di da... I am sorry you have a "URG" number on your account - we cannot sell you a phone. You must go to a corporate AT&T store or call their customer service..... Next..." ME: Help - excuse me....what. I am here to purchase an iPhone - MY iPhone that I have been longing for - for months. I am ready to upgrade my AT&T service, add data and to sign a new 2 year contract. :) I am here - I am ready to BUY.....please explain. nice Apple person....Sorry, it has been our experience that if you have "URG" code on your plan that you have a discount associated with your account and we cannot add an iPhone for you. You must talk to AT&T. Next. ME -- but they don't have phones.....you have phones...NOW. They would make me wait for weeks - they must be ordered. You have a phone now - today and I am at the front of the line. I am ready to give you my money, upgrade my service and my two year committment of more money!!! nice Apple person ....Sorry, you must talk to AT&T. ME: --- not a happy girl! I call AT&T from the Apple store....I don't want to leave - they say they will hold a phone for me if I can get this worked out. AT&T tells me: Yes, you have a tiny weenie discount $14/month on your phone account with your family. Oh, it isn't on your phone - it is on your husband's phone. But yes, the nice Apple person is right, you must remove the discount from your account before you can purchase an iPhone. We can re-add the discount after purchase, but it will take one to two billing cycles for the discount to reappear. No, we cannot backdate the discount. You will lose potentially $28. And by the way, we cannot guarantee how long it will take for the discount to come off your account so that you can purchase the iPhone...could be 30 seconds, could take as long as 24 hours. The only other option is to go to the AT&T store and order your phone from them.... ME: THEY DON'T HAVE PHONES!! I am in line - at the front of the line -- I am inches and a "URG" code away from being an iPhone owner/user extrodinaire. Okay, the discount is on my husband's phone?! How bout if I set up my own account? AT&*T Well in order for us to do that there would be an $18 transfer charge and we would have to have your husband approve the change. ME: not a happy, AT&T customer....."forced" to go to the AT&T store, wait weeks for a iPhone. I can't even break my account off. This is absurd. I would need my husband permission to transfer off. Isn't this the liberated year of the woman! I can set up my own account but I cannot port my number..... All of the above equals a very unhappy, frustrated AT&T customer, with NO iPhone. Hence, I write. Dear AT&T - I am about as unhappy a customer as you can get! I have been loyal to you through the years....@ 10yrs.... Because my spouse works very closely with you and your future technologies - we receive a little $14/mo. discount on our cell phone plan. I appreciate the discount - but I don't appreciate the monopoly you have created with regard to the sale of the iPhone. - I have been left with the option of waiting for weeks by ordering a phone thru you..... OR - Losing $28 in discount....and it's not the money that bothers me. It is the 2 30-50minute phone calls that it will take for me to remove the discount...and then the second call to put the discount back on. It is the funny look that my husband will give me for the hassle. If I walked into the Apple store and smiled at the nice Apple person and said.....I would like an iPhone and I am a new AT&T customer....I would be using an iPhone today. Where is the logic in turning away....new data business - a new 2 year contract. Mr. Business Man, Corp. America...where is the logic in turning away a customer -with money in hand? All this happened a week ago -- I still don't have an iPhone - I still want to buy an iPhone. But thanks to corporate run-around non-sense....I haven't had the gumption to go for it again. those new blackberry's thru Verizon are looking real tempting..... and btw, please don't threaten me with the "service contract fee".....I am long beyond that. Just fix this mess Kind regards, Elizabeth Dear Steve Jobs! How are you? I feel as if I know you since I have been a loyal Apple customer since the first MacIntosh. I didn't buy the first iPhone - sorry, my husband convinced me that I should wait for version 2. Here I am trying to buy version 2. Please read above. What a mess of corporate bureacracy. I am confident that when you set up this corporate deal with AT&T and this latest launch - you wouldn't have agreed to this. I have this confidence because I know you want to attract the "enterprise business customer." The new apps offered with the phone and the ability to make enterprise level upgrades etc. You want the corporate "Blackberry" business. If you are courting business from the "business community" why wouldn't you make it easier for us with a business discount to get this new toy in our hands? I am a recruiter - I talk to technolgy people all day long - I don't think you want me telling my iPhone corporate bureaucratic story.....ease of use, ease of interface, streamline, efficiency. I think all of these adjectives are/were part of the plan. Unfortunately, not my experience. Steve, please look into this problem. It is a corporate disservice....it is making you look bad.** We want the phone - but how much pain will we endure to get it? **PS> 2 people in line behind me - just that day - in that same store. Had the same "URG" code issue. One guy had gone to the AT&T store to have his "discount removed". He was red-faced and panting 'cause he had rushed back and was trying to get a phone before they ran out again. It is more common than you think. I am just a little business woman - potentially the corporate decision maker of tomorrow. Certainly, the household decision maker today. Thanks Steve - I know you will do the right thing. Isn't that why you went back to Apple - ? Kind regards, Elizabeth

Related Entries
• Step-by-Step - the First Automatic Telephone Switching System - Jul 05, 2008

Comments on this Entry:

(iphoneuser on Jul 12, 2008 8:25 PM) Surely, you figured out by now it was because the activation servers went down for a couple hours under the heavy load. I just left mine plugged in and it activated eventually. Bad idea to release firmware in 22 countries worldwide and a new product requiring the same servers all at the same time I guess..

(dejaye on Jul 13, 2008 12:09 AM) I learned from past windows upgrades and new os software...wait a fewmonths you don't always have to be the 1st withnew stuff. I'll stick with 1.1.4 firmware...once apple proves 2me 2.0 version is solid then I'll change.

(TR on Jul 13, 2008 12:18 PM) ihate my iphone. ihate apple. ihate att. They're all .... Here's why. Neither website said I couldn't activate my iphone at apple if I had a FAN discount. 5 hours wasted in line. So I went to att the next day to be second in line and find out att in Sacramneto didn't have any 16GB iphones. Now I get to wait for my iphone to be shipped to att. And to think people complain about the govt not having their crap together.

(Anonymous on Jul 13, 2008 1:25 PM) You say you hate everything that iPhone is associated with.... Yet you are still buying one? hmmmmmm... can you say hypocrite Got this anonymous note. To remind everyone, I still love my iphone and also i still have yet another year to do on my contract with AT&T or is it at&t. I was just shocked that Apple would be so thoughtless. TC

(Michael on Jul 14, 2008 6:13 PM) I like my Blackberry. I do real work with my Blackberry. I never had to wait in line. I'm using the carrier of my choosing, not RIMs.

(Anonymous Coward on Jul 15, 2008 10:57 AM) Typical iPhone Owner: "I love hitting myself in the head with this hammer because it feels so good when I stop..."

Quick Review - Analog samples are placed into digital quantities (quantizing) at specific intervals which means logarithmic (step) quantizing is not a linear process or not all analog values are sampled. However, there are enough samples to reproduce voice but not hi-fidelity sounds. That is, different quantizing systems such as µ-Law and A-Law sample voice differently resulting in different reproduction qualities.

While voice frequencies are linear or sequential, human voice has unique characteristics. That is, quantization levels according to a logarithmic, instead of a linear, process provides smaller quantization levels at lower signal often lower frequency - bass voice. The result is a higher level of reproduction for human voice. A VOCODER-VOice-CODER device allows the DSP-Digital Signal Processor to amplify (quantize) lower or higher frequencies based on the application. That is, the VOCODER can change the logarithms for processing the speech or other input signal such as music. Such a device is also called a COMPANDER-COMpressor and exPANDer. In other words, different Companders will process voice samples differently. The North American PCM-Pulse Code Modulation is called µ-Law (µ from the Greek mu or M or Modulation) which approximates the logarithmic (steps) curve. Mu-Law encoding is where the steps within a cord are all the same size and therefore linear.

PLC-Packet Loss Concealment are advanced voice processing techniques designed to overcome packet loss, bit loss and packet arrival losses or delays. Packets may arrive out-of-order, have excessive delays or be unrecoverable/lost. There are three of more common tools that reduce voice loss or distortion; they include zero insertion (also called zero substitution), waveform substitution replacement and model-based methods.
1 - Zero substitution is simply the replacement of lost bits with zero bits to fill the byte or partial byte lost.
2 - Waveform substitution shown here replaces the bytes lost with those of the previous byte stream (like an instant replay).
3 - Model-based methods use expert-systems advanced voice techniques such as those found in VOCODERS to replace speech lost (e.g. remove syllables) or removed (e.g. no signal "dead air").
According to Alan Percy Director of Market Development for AudioCodes (www.audiocodes.com), on the issue of Packet Loss Concealment, "AudioCodes newest voice coder EG.711 implementation is more aggressive with packet loss concealment and can handle quite high packet loss while still being understandable."

This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.

Related Entries
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• Increased SIP Performance with Stream Control Transmission Protocol - Jul 17, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008

With more than 1,600 trained channel partners, Response Point moves to the lead as a key new player in the IP telephony marketplace. Current Response Point customers and partners in the U.S. and Canada can download SP1 for free at http://www.microsoft.com/responsepoint.

"Small businesses want the same powerful, productive and cost-saving features that big businesses enjoy, but tailored to their needs," said Xuedong Huang, general manager of Microsoft Response Point. "By aligning with industry-leading vendors, SP1 delivers improved performance with many new features like voice over Internet protocol (VoIP) calling, in a complete phone system that can help small businesses and channel partners grow their businesses."

Response Point SP1 builds on the overall ease of version 1 and enables small businesses to immediately take advantage of powerful new features, including session initiation protocol (SIP) trunking for VoIP calling; click-to-call functionality for any contact using the Assistant software; a call history log; and the ability to select music for parked calls and hold time. SP1 is a simple, free download that takes a matter of minutes for a customer or partner to install.

The key point is that Microsoft's telephony solution will be fueling the acceleration for SIP solutions and growth in SIP trunking. However, SIP is more than a different way of processing calls, it's a major revolution is all kinds of communications. If you want more, then go here and I will help you understand why it's so important http://www.techtionary.com/sip/

Response Point Seminar
If you are interested in Response Point, this system will be covered as part of a day-long event focusing on Response Point and OCS-Office Communications Server - Microsoft's enterprise telephony solution. This class will be held on September 16, just before the opening of IT Expo - http://www.itexpo.com.
In the session on ResponsePoint, I will explore the various components in the Response Point system which includes:
• Base Unit - IPX PBX software, voice mail and VoIP gateway
• SIP phones
• Management & Client Software - MAC functions, Outlook integration
• PSTN gateway

Registration for the course and the entire conference is now open. For information and registration go to:
http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

Related Entries
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• Increased SIP Performance with Stream Control Transmission Protocol - Jul 17, 2008

Norwalk, CT, [July 7, 2008] -- Technology Marketing Corporation (TMC), announced today that their TMC University division will offer a Microsoft Office Communications Server and Response Point training course at INTERNET TELEPHONY Conference & EXPO West 2008 in Los Angeles. The day-long course, which includes a 30-minute certification exam, will be held Tuesday, September 16th, day one of the three-day conference.

Titled, 'Introduction to Microsoft Office Communication Server/Response Point', this TMC University course offers an initial training session teaching users how to integrate Microsoft's new enterprise Office Communication Server and small business Response Point platforms into their existing infrastructure.

According to TMC President and conference chairman, Rich Tehrani, TMC University is the only independent program of its kind. And this new Office Communication Server/Response Point course is an overdue addition to the series.

"Since Bill Gates' unveiling of Microsoft Office Communication Server, enterprises continue to determine the most effective way to integrate its considerable advantages into their organizations. This new course gives additional insight and background for enterprise telecom and IT managers to make smart recommendations about what's best for their companies," said TMC president Rich Tehrani.

The program will be taught by Thomas Cross - CEO TECHtionary.com, an innovative communications advisor with considerable expertise in market planning and development, hardware/software design and development, project management, intellectual property in telecommunications, information technology, conferencing, teletraining, telecommuting, groupware, networks, call centers, internet, artificial intelligence and other fields.

Cross commented, Microsoft Office Communication Server is the most profound innovation in telephony since digital PBX systems. "It is very likely Office Communication Server will be a 'must-have' for the enterprise business customer and Response Point for the SMB or branch office communications. By adding this training course to the Los Angeles program, participants can attend a one-day class that prepares them to make recommendations to their companies about a Microsoft Office Communication Server or Response Point strategy." Cross added.

The TMC University Microsoft Office Communication Server/Response Point course consists of sessions covering the following topics:

Introduction and Overview
Office Communication Server business communications scenarios:
• Instant messaging
• On-premise Web conferencing
• On-premise audio/video conferencing including Microsoft's Roundtable
• Telephony

Office Communication Server-PBX Interoperability
This session explores and explains SIP-Session Initiation Protocol and how SIP is used to provide internet telephony functions in an Office Communication Server enterprise telephony solution. This session will explain:

• SIP and versions of SIP used in Office Communication Server
• SIP-to-PBX interoperability
• SIP-to-IP-PBX interoperability
• Office Communication Server and IP-PSTN gateway integration
• Remote office telephony integration

Office Communication Server - Server Roles
In this session, we will explore the various types of servers used in an Office Communication Server environment which include:
• Mediation
• Front End
• Active Directory

Call Flow Scenarios
The following call flow scenarios supported by Office Communication Server will be covered in-depth:
• Telephony users can connect to other telephony users by using Office Communication Server
• Internal telephony users can also communicate with PSTN and PBX users
• Outgoing calls
• Incoming calls

Configuration and Planning
This session is designed to provide the student with an overview of key requirements for planning and implementing Office Communication Server.

Response Point Components
In this session, we will explore the various components in the Response Point system which includes:
• Base Unit - IPX PBX software, voice mail and VoIP gateway
• SIP phones
• Management & Client Software - MAC functions, Outlook integration
• PSTN gateway

This course is sponsored in part by Quintum http://www.quintum.com.

Registration for the course and the entire conference is now open. For information and registration go to:
http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

Anyone interested may also register by visiting http://www.itexpo.com. Limited booth space is still available as well. Vendors interested in exhibiting at the show should contact Dave Rodriguez at 1-203-852-6800, ext. 146.

For information about additional Microsoft Office Communication Server training courses, and the new TMC Office Communication Server newsletter, click on this link: http://www.tmcnet.com/enews/e-newsletters/microsoft-ocs/20071205/Default.htm

Related Entries
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• OSI Understanding the Model of All Models - Jun 23, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008
• Increased SIP Performance with Stream Control Transmission Protocol - Jul 17, 2008

This is a historical view of telephone switching systems. Almon Strowger, a funeral director losing business to a competitor invented the step-by-step "stepper" first automatic telephone switching system patented in 1891. The only known movie of a real stepper is from the Alfred Hitchcock's "Dial M for Murder" - Courtesy Warner Bros. The TECHtionary tutorial also has a photograph of a step-by-step central office.
Here are the processes for step-by-step switching. The animated tutorial is available at http://www.techtionary.com under "S." The process begins telephone with customer number 1 is going to call customer number 2. The following animation demonstrates the steps that occur between Customer 1 dialing the phone number and Customer 2 hearing the phone ring. Here is a photograph from actual stepper CO-Central Office. This illustration shows the inside mechanics and outside appearance of a stepper, the unit that makes sense of the numbers the caller is dialing. This diagram represents the vantage point when a stepper is viewed from the top.
When the caller picks up the receiver, the telephone sends an electrical signal to a Central Office, the location the caller's unique line, along with many others, is identified with. When a stepper at the Central office identifies the line, it sends back dial tone.
This stepper sends a signal to another stepper, telling it the first number dialed by customer 1. That number represents the highest level in the hierarchy used to identify individual callers.

The Allotter sends a signal to the Group Selector, indicating the next step in the hierarchy of lines. This stepper performs both vertical and rotary stepping, as the rotary stepping identifies an intermediate step, and the vertical stepping represents the actual number dialed, a smaller step within the line identification.

The number assigned by the Allotter is sent to another stepper which acts as a Group Selector. The vertical stepper finds the next subgroup Customer 2 belongs to, and moves to the number assigned to this group. Next, within the same stepping unit, the rotary stepper moves further down into the hierarchy. The next four numbers are dialed, which frequently will be transferred to another central office entirely, continuing the same steps as demonstrated. When the final number is dialed, a signal is sent to a stepper acting as a Final Selector, and the call is connected.

Related Entries
• iHate My iPhone Because its iDead - Jul 11, 2008
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• CENTREX Turns New Tricks - Here Comes Microsoft HMC-Hosted Messaging Collaboration - Jun 23, 2008

The animated presentation can be found at: http://www.techtionary.com/podcasts/vpls/

Here is the translation of those acronyms into "no-tech" English. Virtual Private LAN Service allows customers to create VLANs-Virtual Local Area Networks in a metro network or global network using IP-Internet Protocol MPLS-Multi-Protocol Label Switching or VPNS-Virtual Private Network Service. In CEO talk, this means you can connect all the branches in the same city without costing a lot and cities elsewhere "almost" as easily. In the animated presentation, you will see the differences between VPLS and VPNS. There are many others including training, availability, diversity, DR-Disaster recovery, application such as hub-spoke versus mesh networking and others. Check with your provider as YMMV-your mileage may vary.

To begin with, let's see the basic concept behind LAN switching. LAN switching is a Layer 2 (Datalink) concept of switching rather than routing which takes place at Layer 3 (Network). In LAN switching all packets are "flooded" to all locations until they find their destination. Nice idea if you have only a few sites. Originally known as TLS-Transparent LAN-local Area Network Service, Metro-Ethernet, Ethernet Private Line and now often called VPLS-Virtual Private LAN Service, here are some reasons why you should consider this service.
First, it is easy-to-implement with plug-and-play installation.
Next, LAN Switches are cheap.
Third, VPLS provides very flexible BOD-bandwidth on demand options.
Fourth, it is a great solution for same-city customers with many locations.
Here are some reasons against: First, it doesn't grow or scale well to tens of sites and hundreds of users. Second, faster bandwidth doesn't provide QoS or solve flooding of packets due to large applications.

In Layer 3 routing, only the packets that are destined for the other location are sent. That is, packets are routed based on the destination IP address.
Here are some reasons for routing: First, it scales or grows essentially infinitely for customers with domestic and global locations.
Second, routing supports all kinds of IT systems new or legacy.
Third routing provides higher security.
Reasons against routing: First, there is a high cost with routing and routing will always be more expensive than switching.
Second, routing is complex to manage.
Third, routing requires very knowledgeable and technical staff.

I didn't forget VPLS, just needed a minute to get through the basics. VPLS uses MPLS to provide the "seamless" connections for VPLS. Shown in the presentation is the IP-Internet Protocol packet before and with the MPLS "label" attached or "tagged" on as it was originally called. MPLS consists of four elements, label bits, experimental bits, a stack bit and TTL-Time-To-Live bits which indicate the number of Label Switch Routers passed. Shown here is the "multi-protocol" part of MPLS and how it works with the other major networking protocols such as ATM, Frame Relay, Ethernet and others.

As shown in the presentation MPLS is used to connect locations and VLANS together.
In the next slide are the three key access topologies - ethernet-line for two sites, ethernet-LAN for three or more sites and ethernet-access for VPN/internet. This makes implementation and configuration of VLANS really simple.

WHY VPLS - Summary Here are a few business reasons: - Extends LAN infrastructure easily - Expands metro-net to global-net - Migrates Frame Relay to MPLS - Utilizes "pseudowire" approach - Needs "mesh" connections - Connect call centers via SIP - Provide DR-Disaster Recovery for data centers - Seeks greater customer (less carrier) control - Has multi- and broadcast traffic - Building a CDN-Content Delivery Net - Building an overlay multi-carrier network.

VPLS-Virtual Private LAN Service is going to be a great solution for any customer with more than location.

This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.

Related Entries

- Microsoft HMC-Hosted Messaging Collaboration Version 4.5 offers service providers a robust platform to deliver integrated, streamlined communications services to SMBs. A number of partners are working to enhance the HMC 4.5 platform, including BroadSoft Inc., Ensim Corp., ExtendASP, implement.com, Nortel, Parallels, Planet Technologies and Sylantro Systems. These partners have built solutions which range from delivering advanced voice capabilities to empowering end customers with hosting automation tools, as well as developing consulting practices for solution deployments, upgrades and further innovation/customization.

- Nortel is delivering HMC 4.5 resulting in a fully hosted carrier solution that delivers a unified communications experience to SMBs.

- Concentric, a large-scale e-mail service provider is deploying Microsoft Hosted Exchange to combine the productivity benefits of Microsoft Exchange Server 2007 and Microsoft Office Outlook with its enterprise-class applications hosting platform. Concentric will offer new hosted e-mail service offerings for small and medium-sized enterprises.

If you are looking for an end-game for traditional telephony, then here you go.
Maybe it's time for the game to change anyway! I still miss my "crossbar" switch. If you are interested in CENTREX and telephony, you can still see all that at http://www.techtionary.com including images of traditional and next-generation crossbar switches.

Related Entries
• OSI Understanding the Model of All Models - Jun 23, 2008
• SIP: "Threat or Critical Business Tool" - Executive Briefing - June 26-27 - Denver - Westin Westminster - Jun 17, 2008
• BVSD/Lifelong Learning Announces "Internet Studies" Online Courses & Certificate Program - Jul 28, 2008
• Packet Loss Concealment - Zero Insertion - Waveform Substitution - Model-based Methods - Jul 10, 2008
• Microsoft Response Point Service Pack 1 Now Available - Jul 08, 2008
• TMC University Adds Microsoft IP Telephony Course to INTERNET TELEPHONY Conference & EXPO West 2008 - Jul 05, 2008
• SIP-Tips - Security Becomes Paramount - Critical Options - Jun 21, 2008
• 50-Point Comprehensive SIP Security Checklist Included in CTA Convention Course - Jun 20, 2008
• SIP-Planning Guide 2.5 Announced - Jul 31, 2008
• Increased SIP Performance with Stream Control Transmission Protocol - Jul 17, 2008

To understand the OSI-Open Systems Interconnection model one needs to understand that models and standards are used in all industries to create the means to work together called interoperability or in this case, communicate together whether for voice, video, data or any other media. The OSI model touches IT, VoIP/SIP, Security, jacks, cables and every other aspect of our lives, so understanding it in the information technology world is as important as breathing.

Starting with the Physical Layer 1, shown here are the tracks that railroads use to support the trains and boxcars. In the telecom world the tracks are DSL-digital subscriber lines, business lines and trunks, T-1-Transmission Layer One circuits and optical fiber circuits that support streams of digital bits.

Moving up to Layer 2, the Data link layer is where trains, boxcars or in the telecom world, packets are formed. There are literally hundreds of types of data packets such as Ethernet, Frame Relay, ATM, and SCADA as there are types of railroad boxcars. Each data packet format was created for a unique function. In this analogy, we want to show that the train or box car carries the data from one destination to another.

Before we move ahead, let's review two key concepts - routing versus switching
In switching all packets are "flooded" to all locations until they find their destination device. Originally known as TLS-Transparent LAN-local Area Network Service and now often called VPLS-Virtual Private LAN Service, here are some reasons why you should consider this service for your customers: First, it is easy-to-implement with plug-and-play installation. Next, LAN Switches are cheap. Third, VPLS provides very flexible BOD-bandwidth on demand options. Fourth, it is a great solution for same-city customers with many locations. Here are some reasons against: First, it doesn't grow or scale well to tens of sites and hundreds of users Second, faster bandwidth doesn't solve flooding of packets due to large applications.

In routing, only the packets that are destined for the other location are sent. That is, packets are routed based on the destination IP address.
Here are some reasons for routing: First, it scales or grows essentially infinitely for customers with domestic and global locations. Second, routing supports all kinds of IT systems new or legacy
Third routing provides higher security. Reasons against routing: First, there is a high cost with routing and routing will always be more expensive than switching. Second, routing is complex to manage. Third, routing requires very knowledgeable and technical staff.

Now back to the OSI Model, using train metaphor, one key but subtle point is that the packet carries the data without knowledge of the location of its ultimate destination. The knowledge about what routes to take comes from Layer 3 or the Network Layer where routing occurs. Simply, a router supports different protocols or train cars, different routes and different speeds or bandwidth. Importantly, the Network Layer 3 provides routing functions that determine how, when and if a data packet will be sent at all. Again, without going into all the details about firewalls, firewalls operate primarily at Layer 3 controlling incoming and outgoing IP-Internet Protocol packet transmission.

Transport Layer 4 is used to provide reliable confirmation of the packet. Much like when you sign for a FedEx or UPS package, you are confirming receipt of the package. This type of confirmation or protocol is the function of TCP-Transmission Control Protocol which you will see in detail in a few minutes. However, like normal first class mail, UDP or User Datagram Protocol guides the IP-Internet Protocol packet to its destination without confirming receipt.

At Layer 5, the Session Layer additional functions provide for maintaining the connection, in simple terms, logging in and logging off functions.

At Layer 6, the Presentation layer, data is being organized and processed for "presentation" to the user.

At Layer 7, the Applications layer, the user interface and data input such as typing your email or submitting figures in a spreadsheet or database is controlled. As you can see each layer has unique and distinct functions. And for the record, error checking is done at every layer. That is, quality control checks are needed to make sure that the cables are plugged in corrected at Physical Layer 1 all the way up to the Applications Layer 7 where you see and touch the data.

In summary, the OSI model is more than an architecture or framework for IT and communications but a way of life in organizing systems and services efficiently and effectively.

This and more than 3,000 other tutorials can be found at: http://www.techtionary.com.
This presentation is also included in TMC University special course on Microsoft OCS-Office Communications Server at ITexpo.com. For more go here: http://www.tmcnet.com/voip/conference/west-08/tmc-university-microsoft-ocs.htm

This presentation is also included in online/onsite courses SIP 2.0c and for OCS-101 Office Communications Server per person (volume and site license discounts available). Discounts are also available to members of the SIP Forum and MS Partners. For customizing, special discounts, website animations, technical/sales training, technical writing and other services, go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com.