What VoIP on Mobile Can Learn from SS7

Many pundits in the VoIP world have been fixated into thinking that what works on resource-rich PC’s and the broadband Internet should "just work" on mobile devices in a wireless communications world. But in practice it boils down to looking at the mobile communications infrastructure currently available and optimizing the use of resources at hand. And we can often find analogies from the past to guide us towards what makes sense for the future.

SS7 (Signaling System 7) is the inherent protocol for managing legacy PSTN voice services such as call forwarding, voice mail, call transfer and three way calling. eComm 2008 producer Lee Dryburgh was a co-author of the bible for SS7 implementation and has built a business around SS7 development. In Lee’s interview with Telco 2.0 Chief Analyst Martin Geddes discussing The Future of Telecoms and Broadband prior to the recent eComm 2008 event, Martin points out that:

  • The current mobile voice channel used in mobile telephony is quite robust, reliable, scalable and does its job "real well".
  • Trying to deploy VoIP via a client on a mobile platform using 2G or even 3G infrastructure is throwing a lot of technology at a problem that does not exist.
  • Using the Internet as a signaling system for handling what it does best – presence data, text chat, profile information, location information and setting up a phone call – but leaving the voice conversation itself to be carried on the robust, reliable, scalable and proven TDM voice channel – which "does constant bit rate voice, real well" – is really the optimum solution for the foreseeable future.

Martin raises the analogy of Netflix using the Internet as a signaling system to establish and manage a movie rental transaction and the postal system as the bearer. (A similar analogy could be used for Amazon and its system for ordering and distributing books.).

To quote from the interview – retranscribed and with editor’s bold:

[Lee]: Ingeniously Martin has been thinking of the Internet as a means of signaling and coordination rather than always also the best means of delivery. Martin also steps into heretic waters by knocking the fixation with VoIP as a means for moving voice:

[Martin]: Netflix is using the Internet as a signaling mechanism and the postal service as a bearer. And the postal service is a very efficient way of transferring tens or hundreds of gigabytes worth of data….the important lesson is that when you take this to where the cash is – the money is in voice – is that there has been this fixation with voice over IP for a number of years and actually, maybe, and this is heresy, but maybe the good old-fashion phone system is really good at transferring voice. Hey – time division multiplexing does constant bit rate voice real well! So you have to throw an awful lot of [VoIP] technology at a problem [voice quality/delivery] that does not exist [and] to try and persuade anyone to move over to voice over IP. So it is only by understanding the full context and capabilities of each of these systems that you start to think [that], hey, actually the Internet is good at allowing new forms of signaling to evolve faster than what SS7 or whatever may have allowed…so why don’t we focus on enabling the IP part to do what it does well which is how do we enable the rendezvous’ in front of this phone call, how do we return signals and presence data and the little picture of where I am at, location information to help people make phone calls at the right time…stop worrying about trying to do voice over IP until the technology is super duper mature – until we can not possibly afford to maintain two networks which is quite a long way away still and let the phone network do what it does well which is phone calls.

[Lee] So, for 2008, you’re promoting TDM! [Martin concurs]

Sounds like iSkoot, IM+ for Skype and Mobivox, along with 3’s Skypephone service, may be on to something here. I can only hope that VoIP Supply’s new blog, Mobile VoIP Review, can keep issues such as this and the backhaul limitations in perspective such as not to raise expectations too high until we have the required infrastructure for full mobile VoIP in three to five years.

Tags: Mobile VoIP, SS7, Lee Dryburgh, Martin Geddes, Netflix, TDM, eComm 2008, iSkoot, IM+ for Skype, Mobivox, Skypephone

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About Jim Courtney

Bringing over thirty years' experience in the sales, marketing and management of cutting edge technology businesses.


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