Last week the VoLGA Forum (Voice over LTE via Generic Acces), released a completed set of technical specifications for Voice over Long Term Evolution. Having this specification is an important step, since it will allow mobile network operators to offer voice and SMS services on LTE networks.
There are no industry agreed upon standards for voice and SMS over the Long Term Evolution standard. Right now, LTE only supports data services.
A number of alternative solutions have been analyzed in 3GPP to be the successor to the circuit switched voice architecture by the 3G Partnership Project (3GPP). They include:
- CSFB, or Circuit Switched Fallback, essentially allows devices to revert to GSM or UMTS for incoming and outgoing voice calls.
- The VoLGA Forum (Voice over LTE via Generic Access), supported by companies like Alcatel-Lucent, HTC, LG, Motorola, Samsung, ZTE, and Deutsch Telekom. The VoLGA concept, advanced by T-Mobile and vendors like Ericsson and Kineto Wireless, essentially “tunnels” circuit voice over a packet-based radio connection.
- IP Multimedia Subsystem (IMS): An architectural framework for delivering Internet Protocol (IP) multimedia services. To ease the integration with the Internet, IMS uses IETF protocols wherever possible, e.g. Session Initiation Protocol (SIP).
3GPP has specified CS fallback, reverting to earlier GSM or UMTS standards for voice. Many network operators are hoping for IMS in the long-term, which will carry voice and video on the IP network. However both leave LTE exposed on the voice front at least over the next couple of years. VOLGA (pdf), it is thought, could deliver voice over LTE more quickly and with less overhead than IMS.
Meanwhile, Kineto Wireless, which provides the WiFi phone solution for T-Mobile, announced a mobile VoIP application aimed at mobile operators. The new VoIP solution enables mobile operators to offer customizable and competitive mobile VoIP service through their existing voice network infrastructure using WiFi phones. Their UMA effort (Unlicensed Mobile Access) was initiated in January 2004 by 14 leading operators and vendors in the wireless industry.
The application also helps mobile operators overcome the growing threat of over-the-top competitive telecom services like Skype, Google Voice and Truphone, said Mark Powell, vice president and general manager of Kineto’s Client Business Unit.
