Mobile network operators and their equipment suppliers are working hard to make telephony over data-oriented LTE (Long-Term Evolution) mobile networks a reality, with the number of demos at Mobile World Congress a sign they are getting closer.
The GSM Association (GSMA), an industry body, is conducting a demonstration with U.S. operator Verizon using LG Electronics' Revolution smartphone and a network from Alcatel-Lucent. Verizon is also involved in a second demo that uses a smartphone from Samsung and a network from Ericsson.
So far, Verizon Wireless has been the most vocal operator about the need for telephony in its LTE network, and has said it expects to launch commercial Voice over LTE services in 2012.
Demonstrating Voice over LTE -- which is completely IP-based and uses SIP (Session Initiation Protocol) to set up the call -- is fairly dull because it works just like a regular phone call, but for the industry it is an important step, according to Dan Warren, senior director of technology at the GSMA. The availability of standardized voice will help LTE take off more quickly, he said.
The voice quality in the GSMA-LG-Alcatel-Lucent demo sounded like an improvement over current mobile networks, despite the less-than-perfect circumstances. The LG smartphone contained an HD Voice codec, which uses more bandwidth than regular voice codecs to improve voice quality. HD Voice is already available in some 3G networks, but going all IP-will make the technology easier to implement, Warren said. LTE's lower network latency, compared to 3G, will also improve voice quality when calling over long distances, Warren said.
In November 2009, a group of 12 mobile operators and vendors formed the group One Voice to ensure widespread adoption of a common standard for voice over LTE and to avoid fragmentation on technical issues. The project has since attracted more members and changed its name to the GSMA Voice over LTE Initiative where, under the leadership of the GSMA, work on the Voice over LTE (VoLTE) specification has been progressing steadily.
Most of the work has been finalized. In March, the roaming part of the specification will also be ready, according to Warren. In September, a number of handset and network vendors will get together under the MultiService Forum banner to do interoperability tests. A Vodafone lab in Düsseldorf and a China Mobile Research Lab in Beijing will be used to conduct the tests.
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