Major operators back IMS for voice over LTE

When it comes to how voice and SMS is going to be delivered over LTE, operators, with the exception of T-Mobile International, have been silent. But this week, fearing fragmentation resulting in the many approaches that have been put on the table, some of the world's largest mobile operators, infrastructure vendors and handset makers have joined to push a standardized way to deliver voice using IP Multimedia Subsystem (IMS).

AT&T, France Telecom, Orange, Telefonica, TeliaSonera, Verizon Wireless and Vodafone have joined Alcatel-Lucent, Ericsson, Nokia Siemens Networks, Nokia, Samsung and Sony Ericsson to push an initiative called One Voice.

The 3G Partnership Project (3GPP), in charge of creating LTE standards, has endorsed the use of IMS architecture, which, on a basic level, replaces an operator's back-end network architecture with an all IP-based system, making it easy to deploy services like SMS and voice via a VoIP-type service. The group is looking to use a technical profile of the 3GPP IMS specifications that will be required to deliver basic voice and SMS and do it in about 12 to 18 months. The work will be sent back to 3GPP.

Meanwhile, T-Mobile, along with some of these same vendors, has been pushing for a compromise called VoLGA (Voice over LTE via Generic Access) that breaks mobile voice and messaging apart from the IP-based LTE network and puts it on the existing 3GPP Generic Access Network (GAN). Development will continue as the interim step to IMS, but it appears that most operators would rather move straight to IMS, which critics say may not be mature enough to handle VoIP in the next year.

For more:
- see this Unstrung article [1]
- read this FierceWireless article [2]

Related articles:
T-Mobile, vendors establish forum to enable voice over LTE [3]
LTE voice: T-Mobile alone in pushing specs [4]
LTE: Operators split over support for legacy voice services [5]
Is voice over LTE a conundrum? [6]
Nokia Siemens Networks proposes different technology for voice over LTE [7]