February 2008 Archives

After it seems like an eternity of waiting, Verizon is finally starting the process to install Fios on my street.  They have most of my home town of Orchard Park, NY strung with fiberoptic cable from pole to pole, but those of us that are serviced by underground cables were last in line.

Anyhow, now I understand why Verizon plans on spending an average of $1,000 per household to install Fios.  First all the utility companies (gas, water, telephone, cable...) all have to mark/flag their lines.  (Our front lawn looks like a miniature golf course)  Then the Verizon guys come out and....sit in the truck.  So far this truck has been parked in front of my house for two days with at least two guys sitting in it.  God knows what they are doing, but there they sit - idling the engine.

$1,000 per household?  Verizon has spent that so far just in fueling this idling truck.

Thankfully the battle is now over between the competing high-definition DVD formats and Sony's Blu-ray format is the victor.  Fortunately, this played out a lot faster than the Beta/VHS battle that lasted through most of the 80's (BTW: to this day, I still have one of each in my AV cabinet) Settling the Blu-ray / HD-DVD battle will end much of the consumer confusion and let us get back to spending our "economic stimulus" checks when they arrive later this summer.

Now that this is behind us, what can we learn from this?

#1 - The first to market advantage does not necessarily create a victor.  It's all about market positioning and market might.  Sony and Panasonic out positioned Toshiba.

#2 - Better technology will not win the war.  As with the Beta/VHS war, it's not clear that the better technology actually won the war.  HD-DVD did have a number of features and capabilities that Blu-ray is just now introducing.

#3 - Customers don't always control who wins.  In the end, the movie distribution houses made the choice, not the consumers.  As bad as the video rental stores and NetFlix of the world didn't want two formats, the movie distributors hated the specter of two formats even more.

#4 Being stubborn costs $.  The biggest mistake is that the Sony and Toshiba didn't sit down and come up with a compromise format from the beginning.  Would the few months it would have taken to work out the details really have hurt the market?  I doubt it.  Did having two formats for the last two years hurt the market and cost millions of dollars?  Absolutely.

Now back to our regularly scheduled program....

Another great turnout for today's two webinars on "Fax - SIP+T.38 to the Rescue", thanks everyone for participating.

And more great questions:

Q: (Brian) a slide showed FAX machine - T.38 gateway - T.38 Gateway - FAX Machine.  I was under the impression that once a FAX was converted into T.38 It coudlnt be changed back into a audio FAX call.
A: Actually, a fax can be converted to T.38 and back no problem or loss of information.  This is what happens with virtually all fax calls that are transported over VoIP carriers.  It works fine.

Q: (Darren) Do your gateways support V.34 fax over T.38? Does your T.38 fax SDK? If not, where is this on your development roadmap? We have identified this as one of the major monetary objections to using T.38 instead of TDM.
A: Our T.38 Fax SDK does support V.34 transport, but at this time our gateways are limited to V.17 speeds when used with T.38.  We are working toward delivering V.34 with T.38 on our current gateways and hope to announce our formal plans soon.

Q: (Darren) Is your T.38 fax SDK available for Linux?
A: Our T.38 Fax SDK is for Windows, but there are many others on the market and do believe a few of them support Linux.  We've had many customers use T.38 SDKs from one vendor and our gateways with no interoperability issues.

Q: (Yaniv) When using an analog MediaPack gateway, can the DID/DNIS information be passed to the SIP application?
A: Absolutely - is appears in the SIP INVITE.

Q: (Roger) Will these slides/audio be available?
A: Yes, a previously recorded version of the webinar is available at: http://www.tmcnet.com/webinar/audiocodes5/

Just as a reminder, the questions from the previous session can be found at:  http://blog.tmcnet.com/sip-invite/sip/fax-webinar-qa.asp

You can address your questions to me at:  alan.percy@audiocodes.com

Thanks again to all those that participated in the Webinar titled "Fax - SIP+T.38 to the Rescue" we held a few weeks ago.  As noted in a previous blog post, it was a very busy webinar.  You can listen to the on-demand recording of the webinar at: http://www.tmcnet.com/webinar/audiocodes5/

As noted on the webinar, we had run out of time and were unable to get to all the great questions posed by the attendees. Find below some of the Questions and Answers that we didn't have time to address:

Q: (from Scott) is T.37 being employed and deployed?
A: T.37 is used in some messaging applications, but it is quite different than T.38.  T.37 uses email technology to transport documents and thus is not real-time.  It's great for store and forward applications, but not widely used or supported by carriers. For more on T.37, visit wikipedia

Q: (from Scott) who offers T.38 SDK's for fax API's?
A: AudioCodes and a number of other manufacturers offer a T.38 SDKs.  AudioCodes has certified our gateways with a number of other other third-party manufacturer's T.38 software.

Q: (from Tim) I think T.38 was specified to use "UDPTL" or TCP - with RTP only added to the spec recently. What do people use in practice?
A: We are using UDPTL, TCP adds addional timing issues into the equation.

Q: (from Jayaprakash) Does Gateways always do the Fax tone detection? or it is Fax Application server responsibility?
A: Our gateways can detect the CNG fax tone, which makes fax detection much easier for application developers.  Detection can be done by the application servers, but it is much harder and less accurate.

Q: (from Oliver) Which SIP trunking carriers support T.38?
A: AT&T and Quest are two carriers which have been certified to work very well.  Others are in lab testing.

Q: (from Edward) How much bandwidth required for SIP+T.38 normally ?
A: T.38 with triple redundancy and operating with V.17 speeds would use roughly 48 kbps.  Less redundency on good networks would use even less.   In comparison, a fax over G.711 would require close to 80 kbps.

Q: (from Prashanth) Can T.38 fax be done using other codecs than G.711?
A: No, transporting fax via T.38 is done instead of using a voice coder (like G.711).  Other voice coders compress the audio and are even less reliable than G.711.

Q: (from Yossman) Is your media gateway compatible with other brand devices that also supports SIP+T.38 ?
A: Yes, AudioCodes media gateways are many times deployed in mixed network environments and have excellent compatibility and reliability.

Q: (from Shawn) do you need to have a t.38 media server on both sides (sending and receiving)?
A: For T.38 to work, both ends of the IP connection need to support T.38

Q: (from Anil) Does these Media Gateways also have similar issues like Denial of service and other attacks and how do we solve this?
A: (While not the topic of this thread, this is a good question) Security is always a big concern and media gateways do need to be hardened to protect against attack.  AudioCodes gateways have been hardened and passed stringent DoD certifications for deployment in DoD networks. 

There are many more questions and I'll post more in the next few days....