January 02, 2009

Know Thy VoIP before Taking Pulse

The last week or so, there have been flurry of blog posts taking issue on either side of the question “VoIP: Dead or Alive?”. It might have been started by Jonathan Christensen of Skype provocatively declaring that VoIP to be dead. Subsequently most of the leading VoIP bloggers have shared their opinions. Those arguing VoIP to be alive and vibrant point to active voice services that use IP in some form or other; those who think otherwise point to many failed companies or seem to suggest that the only important aspect of VoIP is the transport mechanism and that voice transported on the Internet and hence VoIP is passé. Jeff Pulver, the pope of VoIP (actually I consider him to be a vishwamitra; but I am afraid only a few will get that) is mutedly points out that VoIP is more than transport technology. If it comes to that one can argue that TDM to be a “subnetwork” that comprises the concatenated network that is Internet and declare everything is VoIP. So what is VoIP for me?

Firstly, VoIP should use a rich signaling mechanism that extends all the way to the end device the user is using. This is critical because this will allow users to exchange meta information like purpose of the call, criticality of the call, authentication information of the far-end user and so on. Depending on the user’s current status, the device can deliver the information in a less intrusive manner. Typical PSTN phones do not have this flexibility, even though the industry tried to introduce this capability using ADSI phones. This means that those VoIP services that use ATAs coupled with traditional phones are not really VoIP because users can not benefit from message oriented signaling like SIP.

Secondly, the service should really believe in “intelligence at the end” mantra and its close cousin “stupid network”. So if a service lobotomizes the intelligence at the end or if it inserts itself in the middle destructively, then it is not VoIP.

Thirdly, notwithstanding voice in the title, VoIP must be multi-modal with the ability for the ends to dynamically add/drop/change mode(s), without much interference from the “Middle”.

Have you seen an animal that meets all these requirements? Has it not lived up to your expectations? Do think such an animal will ever fail?

Posted by aswath at January 2, 2009 11:09 AM
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