Session Border Controllers & Media Gateways Soup Up SIP Communications

April 10, 2008
MG’s & SBC’s Dramatically Change the Enterprise Communications Landscape
 
The following pictutorials are examples of customer applications of SBC-Session Border Controllers with an emphasis on MG-Media Gateways:
- SBC-Session Border Controllers connect SIP networks
- MG-Media Gateways Next-Generation Networks
- Customer Applications of Media Gateways
 
A few basics - SBC-Session Border Controllers connect SIP devices to the PSTN and MG-
Media Gateways also connect SIP devices to the PSTN. The difference is SBC's are provider-class systems, whereas MG's are designed for local connection to the PSTN. 
The primary function of the SBC is to serve, basically, as a SIP-aware NATing Firewall. SC-Session Controllers or SBC-Session Border Controllers are access devices operate at Layer 5 Session Layer, where as routers operate at Layer 3 Network.   Some of the key SBC-SC functions are:
- Secure network peering - private and public to enhance performance
- Topology hiding - using various types of inter-AS-Autonomous System features as well as separating media (voice) and hide signaling (IP addresses) data streams (traffic)
- Border call routing - routing at AS level rather than with interior protocols
- Interoperability - access/restrict to reduce voice spam
- QoS & Call Admission Control - load/jitter correction
- Billing systems interoperability - reduce billing errors
- NAT-Network Address Translation - routing for maximum performance
- DNS-Domain Name Service and ENUM (E.164) support
- CALEA-Communications Assistance for Law Enforcement Act
- E911 support
- Compatibility with customer billing
- Dialect conversion
- Protocol conversion
- Codec conversion
- Firewall restrictions
- Wholesale and Transit peering - various types of stateful (interconnect different networks such as H.323, MGCP-Media Gateway Control Protocol and SIP-Session Initiation Protocol) and stateless (same networks) Session Controllers exist depending on the VoIP Network features required.
- Other features, check with manufacturer.
 
In other words, even a high-volume company might only need a few MG's or SBC's to provide carrier-class performance including a vast array of features.
In the pictutorial are some examples of ON/OFFnet SIP calling via MG & SBC
 
- ONnet SIP Calls & ONnet Conference Calls.
     - Key point: no need for MG or PSTN with SIP network peering even fewer GW needed.
 
- OFFnet SIP Call Flows
     - Key point: No need for local PBX/key systems or trunks with the need for only a few gateways nationally or globally.
-  OFFnet PSTN calls via MG-Media Gateways
- Automatic MG call re-routing in case of failure to backup MG
- Automatic call re-routing in case of failure via SBC
 
Shown in the pictutorial are some examples of Common SIP Calls:
- Call Signaling via Proxy server
- Media Transmission Directly
- Parallel Forking Simultaneous Ring
- Sequential Forking - Sequential Ring - "Call Office, Call Home, Go to Voice Mail"
- Call Authentication via Proxy server
- Redirect Call Forwarding via Proxy server – UAB, then Call Processing - via Proxy - UAC
 
Media Gateways
That is, MG's would be strategically located across the continental or world and interface the PSTN only as necessary.
Shown in the pictutorial are some examples of customer applications of MG-Media Gateways:
- Connection of IP-PBX to PSTN
- Connection of IP-PBX to PSTN & SIP trunk provider
- Survivable connection to SIP trunk provider
- Connection of PBX & IP-PBX to PSTN & SIP trunk provider
     Hairpin or Hairpinning - calls come in from PSTN and routed back out to PSTN
- Connection of IP-PBX to Hosted VoIP provider
- Connection of IP-PBX & PSTN to Microsoft OCS Server
- Multiple SIP-OCS proxies - SIP to SIP calls, TDM to TDM calls and SIP to TDM calls
 
If you want to know more, this information is also part of OCS-101 and SIP Essentials 2.0c available in the onsite and online courses. The online version is $299 for SIP 2.0c and for $499 as part of OCS-101 Office Communications Server online version per person or less with discounts. For more information go to http://www.techtionary.com or please call Tom Cross at 303-594-1694 or cross@gocross.com Discounts are also available to members of the SIP Forum. 
 


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