A new initiative has been publicly announced: to make IMS prevalent over the next gen LTE cellular networks. It comes from a distinguished set of companies: Orange, Telefonica, TeliaSonera, Vodafone, Alcatel-Lucent, Ericsson, Nokia Siemens Networks, and Sony Ericsson.From the foreword of the initial proposal spec to 3GPP (PDF).
3GPP has worked with the IMS almost ten years and there exist thousands of pages, in different specifications, that cover IMS related functionalities. In the meantime, a sophisticated architecture and feature set has been developed. Not all of this functionality is needed for an initial deployment of a cellular IMS based VoIP network. Moreover, 3GPP has specified multiple, different ways to complete single functions (e.g. authentication, session setup, supplementary service execution, bearer setup) which increases complexity of the IMS. To help industry secure a common standardized IMS voice solution, this specification defines a common recommended feature set and selects one recommended option when multiple options exist for single functionality.
I have written already on my VoIP Survivor blog why this initiative is a death blow to Mobile VoIP startups. So the focus here is on some aspects in this foreword:
IMS is alive and kicking, but too complex:
3GPP has worked with the IMS almost ten years and there exist thousands of pages, in different specifications, that cover IMS related functionalities.
If there is any real drawback to IMS it's that it is way too complex. There are too many RFCs and 3GPP documents to follow in order to actually implement it properly from the ground up. So yes, operators and vendors have been working for ten years on IMS, but there's nothing yet to show the end customers.
You can do anything with IMS:
In the meantime, a sophisticated architecture and feature set has been developed. Not all of this functionality is needed for an initial deployment of a cellular IMS based VoIP network.
For me, this simply means that it is too complex (did I say that already?).
The architecture of IMS has been designed from the ground up in order to allow an extensive feature set to emerge. My guess is that this fact alone is the cause for the non-adoption of IMS by operators so far.
But it also positions IMS in a very comfortable place, where it can actually be used for years to come as the architecture of the operator's core networks for their future services--simply because it took them into account in the design stage.
The "two Jews three opinions" syndrome:
Moreover, 3GPP has specified multiple, different ways to complete single functions (e.g. authentication, session setup, supplementary service execution, bearer setup) which increases complexity of the IMS.
This is what I call the two-Jews-three-opinions syndrome which is too prevalent with standards, and in this case IMS is no exception: everything that is done over IMS can be done in multiple ways. This means that developers have a hard time selecting which option to choose, and interoperability is quite impossible to achieve.
These guys are serious:
To help industry secure a common standardized IMS voice solution, this specification defines a common recommended feature set and selects one recommended option when multiple options exist for single functionality.
LTE moves the cellular network to an all-IP infrastructure. This leaves operators no choice but to move towards VoIP solutions for their basic voice and SMS services. While the mobile industry has already selected IMS for the task, some (me included) have questioned the validity of the decision and the possibility of it ever coming to fruition. But this new "One Voice" initiative proves me wrong: by reducing IMS to the basic needs of voice and IMS, operators will now be able to start adopting IMS in ways that were impossible up until today.
Other opinions on One Voice: While I have my own opinions, there are others who have written their thoughts on One Voice. Here are a few of them that provide some other angles on this story:
* Martin Sauter provides his insights on One Voice from a political and a technical viewpoints.
* Caroline Gabriel covers the dynamics that brought about the One Voice initiative.
* Stacey Higginbotham points at the missing players in One Voice.
