A standards-compliant voice call in LTE was recently made by Nokia Siemens Networks at its R&D centers in Germany and Finland. While the focus of most LTE trials and deployment plans are on data service, LTE also has important benefits for voice service as it offers the highest spectral efficiency for voice. Also, the delivery of voice over LTE networks means operators will in the future be able to provide all services over the same all-IP network, driving down the expense of operating parallel legacy and LTE networks.
The call conducted by Nokia Siemens Networks used a configuration of commercially ready LTE equipment fully 3GPP-compliant from end to end. The call was made from a laptop equipped with the Nokia Siemens Networks Communication Suite “softphone” application and an LG Electronics LTE USB Datacard. The network used for the call included commercial versions of Nokia Siemens Networks’ Flexi Multiradio Base Station with 3GPP-compliant software, Evolved Packet Core (EPC) and Fast Track VoLTE solutions.
The EPC provides data connectivity for LTE networks, while the Nokia Siemens Networks Fast Track VoLTE solution provides fully 3GPP-standardized IP Multimedia Subsystem (IMS) functionality to handle call control for mobile voice traffic in LTE networks. Fast Track VoLTE is fully aligned with the One Voice initiative recently announced by Nokia Siemens Networks and other industry stakeholders.
To further demonstrate the viability of 3GPP-standardized voice, Nokia Siemens Networks’ will also soon conduct VoLTE test calls with a fully implemented IMS system. In a separate related development, Nokia Siemens Networks recently conducted a voice call using TD-LTE equipment in Hangzhou, China.
“Voice will continue to be an important application in mobile networks now and in the future,” said Jürgen Walter, head of converged core, Nokia Siemens Networks. “This successful LTE voice call takes us a step closer to realizing commercial voice over LTE services. And the fact that we can now demonstrate this functionality with both FDD and TDD variants of LTE means that we are well on track to successfully introduce standardized LTE voice and SMS to all parts of the world.”