Updated with T-Mobile US comments.
Voice over LTE services are set to receive a significant boost as a pair of unlikely partners announced plans to enable VoLTE interoperability beginning in 2015.
Today, Verizon Communications and AT&T announced plans to allow their respective customers to conduct VoLTE calls between their two networks. The companies noted that their respective engineers are working through requirements, beginning with lab tests and plans to move towards field trials.
The work is being conducted in coordination with the GSMA, which through its Network 2020 initiative has encouraged mobile operators to work together on IP-related communication services like VoLTE and rich communications services.
“Interoperability among all VoLTE providers takes connectivity to the next level with HD quality voice and additional features that customers want,” said Verizon CTO Tony Melone, in a statement. “We’re pleased to be working with AT&T as our first interoperating carrier, and we look forward to working with other operators as VoLTE continues to grow.”
“We are pleased to work with Verizon on this initiative,” added Krish Prabhu, CTO of AT&T and president of AT&T Labs. “We continue to work with others in the industry on similar collaborative arrangements and hope to see similar collaboration across the industry in the near future.”
AT&T Mobility earlier this year rolled out VoLTE services covering select markets. Verizon Wireless in September rolled out a networkwide offering under the Advanced Calling 1.0 brand just ahead of the launch of Apple’s latest iPhone 6 models. That device launch was noted by many analysts as a catalyst for greater focus by operators on boosting their VoLTE services both in reach of the device as well as Apple’s embedded FaceTime application, which the carrier-derived VoLTE services will be competing against.
VoLTE push
Unlike over-the-top applications such as FaceTime and Skype, which rely on voice-over-Internet Protocol technology to transmit both video and voice, the initial carrier VoLTE services have been limited to only working across their respective networks. That limitation is seen as a limiting factor to consumer uptake, as well as the current dearth of devices compatible with VoLTE services. Beyond the iPhone 6 and 6 Plus, Verizon Wireless’ VoLTE service launched with support on the Samsung Galaxy S5 and LG G2 devices, while AT&T Mobility’s service launched with support on only the Samsung Galaxy S4 Mini.
T-Mobile US, which also launched VoLTE services earlier this year, was not included in the latest interoperability announcement, though CEO John Legere took to Twitter to state that the company has been testing cross-carrier VoLTE compatibility and that “We’re ready when you guys are!”
Sprint at this point is sitting out the VoLTE push, focusing instead on CDMA2000 1x-Advanced, HD Voice and voice-over-Wi-Fi technologies.
The move to VoLTE will allow wireless carriers to transmit voice traffic more efficiently and eventually shutter legacy 2G and 3G networks that are currently burdened with carrying all voice traffic and a good portion of data traffic. Analysts noted in an RCR Wireless News report last year that carriers could achieve up to 40% more spectral efficiency running voice traffic over their LTE networks compared with legacy systems.
Another option for mobile operators is the WebRTC standard, which is a platform that uses JavaScript APIs to support real-time communications through standard Web browsers.
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