SIP Sessions

Is IMS Dead?

Last week I spent two days at MobiMedia 2009 in London. This is a small conference in which the latest developments in the academic world with regard to things like distributed video compression and novel wireless compression technologies are discussed. The part that I was involved with was a panel about the future of wireless multimedia services. The panel started with a presentation of a study done by Ofcom, the UK regulator, showing that under certain scenarios there will not be sufficient wireless spectrum available in 10 years. This was countered by researchers from the University of Edinborough and NTT docomo, who indicated that it is possible to increase the efficiency of the currently used spectrum not only by using even more efficient compression mechanisms but simply by using more intelligent bandwidth allocation schemes.

This discussion led somehow to the question of what mobile operators should be doing in order to make their subscribers' lives more exciting in the future and finally to the question of whether IMS is dead, and if not, then why is it not deployed yet?

Thinking about this, IMS offers some good points. It enables mobile operators to continue using the same business model they are used to, namely providing telephony services and supporting roaming. Further, as operators can bundle the call establishment with guaranteed QoS they could offer qualitatively better services than VoIP providers who do not own a network. Also, the IMS architecture enables the operator to fulfill regulatory requirements with regard to emergency services and call interception in a rather straight forward manner. Finally, bundling voice services with other services should be easier in an all-IP environment thereby enabling the operator to offer a million new exciting and revenuegenerating services. But, all of these points could be achieved in a simpler manner.

With all of these positive points, one can only wonder why operators are not tearing up their SS7 infrastructures and are not spending billions on IMS solutions -which would have as a side effect that thousands of jobs would be saved, the economy would prosper, the stock market would soar and with every one becoming prosperous, world peace would finally become a reality.

 If we leave aside the usual ranting about the complexity of IMS and how it undermines the open concept of the Internet and reintroduces the closed-wall garden model, I would say that IMS at this stage is still a bit too early. In order to be able to fulfill the promise of IMS, namely more services and the integration of voice, video, text, presence and web applications, a mobile operator will need two important components which are not available today; namely high bandwidth wireless access and end devices that are designed to offer more than telephony services.

Using VoIP over wireless networks is in general less efficient than using the circuit switched technology we have today. The mobile phones available today are designed to offer telephony services. Hence, even if an operator started offering some IP-based services, the number of people who would benefit from these services would be limited.

So is this final verdict?

Well I am not sure. With the mobile operators moving to LTE with a simplified all-IP network and much higher wireless access bandwidth, I would not be surprised if IMS becomes all the rage again. Regardless of all of its shortcomings, IMS or at least SIP-based signaling is still the only viable alternative to SS7. So if mobile operators see themselves as providers of telephony services and not just bit-pipes, then IMS will most likely be their first choice as an IP-based signaling infrastructure.  On the other hand, with high access speeds there is no need to worry about QoS so one of the alleged advantages of IMS would disappear as well.

With regard to the end devices, we have seen in the last one to two years an increasing number of phones that are powerful enough to support a wide range of multimedia and web applications as well as being easy to use. However, any application that can be built on top of IMS can be provided over a much simpler SIP infrastructure as well.

With this in mind, I am still hopeful that one day my mobile phone will truly be a an IP-device offering integrated voice, video and web applications (whatever this means :).