February 11, 2005

VoIP (as practiced today) is “Intelligent” After All

Last week Tom Evslin wrote why VoIP will be known for its features. That entry is made up of three components:

  1. The list of features his current VoIP service provider (Vonage, but it is incidental) make them available to him are very useful to him.
  2. The price difference between PSTN and VoIP is inconsequential. (It is not clear whether he anticipates that these price differences will disappear in time or that the feature set will be so attractive that potential users will not even look at the price advantage.)
  3. PSTN service providers, hobbled by the Intelligent Network, will never be able to match the features facilitated by VoIP technology.

The purpose of this note is to take issue with some of the logic and to suggest that for VoIP to truly deliver on its promise, we have to think differently.

The following is a summary of the features he likes, followed by one way I think how PSTN may be able to offer the same feature without “shoehorning” them into their “intelligent” network.

  • He really likes the portability feature. He is able to go to his beach house or the winter place and receive calls meant for the primary residence. More importantly, there is really no setup excepting connecting the ATA into the network at the new place.
    Of course a PSTN service provider can easily imitate this feature by asking the subscriber to dial an 800 number which will note down the number of the new place and automatically provision the call forwarding feature at the switch associated with the primary residence. Since I am assuming flat rate pricing for PSTN as well, there is no need for additional charge for forwarded calls. Of course this scheme may not work if the new place is behind certain PBXs; but then again VoIP has its own difficulties in the corporate environments due to firewalls.
  • VoIP service providers offer simultaneous ringing feature. Indeed early SIP documents called this “forking” and many in the community were claiming this to be a unique capability of SIP (not VoIP) architecture.
    Excepting that Cincinnati Bell (now you can guess how long ago) offered this as a tariffed service and either they or their partners had a patent on it as well. Of course in the PBX environment this was a standard feature.
  • The third feature he benefits from is the fabled Virtual numbers. He states that he does not incur any usage charges. Of course this is true, but we know that this service is viable because of the access charge regime that many VoIP proponents oppose.
    Be that as it may. This feat is not accomplished by VoIP technology. After all the call directed to the virtual number comes to a PSTN switch (most probably a CLEC partner) which forwards it to the designated end-point. A PSTN service provider could do the same, except the current regulatory regime may very well prohibit an ILEC to strike a partnership with another service provider.
  • Finally, his VoIP service provider offers all the features available in PSTN. But more importantly it is very easy to manage these features and there is a night and day difference when comparing the user experiences between VoIP and PSTN environments.
    He fails to mention the enhanced features available to ADSI phones (granted a market failure; but we are comparing technologies here) or new services like Verizon iobi.

He concludes by saying that even if all these features were/are/can be implemented in PSTN, it is “almost impossible to shoehorn [them] into the over-complex “intelligent” networks of the traditional carriers, it is the VoIP providers like Vonage who are making these features practically available.” This veiled reference to “The Rise of Stupid Network” is standard fare and has become this industry’s “shibboleth”. From an architectural point of view there is no difference between PSTN and VoIP. In IN-PSTN architecture, there are SSP – consisting of call control logic and switching fabric, SCP and IP (Intelligent Peripheral). VoIP architecture used by service providers consists of Proxy servers/Gatekeeper/Call Agent and media servers. The routers take on the role of switching fabric; but they are not so tightly integrated with the call control logic. But from feature invocation and execution point of view, the switching fabric is not all that critical. It is in this respect I claim that VoIP architecture is as “intelligent” as the traditional PSTN. So, if Vonage and others offer these features while traditional PSTN service providers procrastinate, the explanations lie elsewhere. In other words, invoking “intelligent” network comes across as “sibboleth”.

My intention here is not to be argumentative. When Tom speaks others listen. Hence I am concerned that we as a community may focus our attention on wrong things. It is true that certain features are possible only with IP Communication; PSTN can never hope to provide them. The most important of these is that IP Communication facilitates any-to-any communication. Here I do not mean P2P – a hijacked term that requires many nodes– and “serverless” – which requires many in the community. Let me coin a new term – “autonomous”, wherein two or more communicate directly with each other without the intervention of any special service providers or special nodes but use well established IP services provided by commodity providers. Secondly, with IP Communications one can use any application(s) and any granularity of network resource; PSTN at most can offer services that are a multiple of a specific base capability. Finally, the current level of technology and its price points, allows us to offer sophisticated user interface. None of the current set of VoIP service providers allow for any of them. Indeed, they behave like the hated “Bellheads” and charge differently for different applications. So let us focus on these features now instead of waiting for the mythical “tipping point”.

Posted by aswath at February 11, 2005 11:44 PM
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