Telefónica has achieved a breakthrough in Germany: the network operator is the first in the world to demonstrate technology that transfers voice calls seamlessly from an LTE network to a UMTS mobile network while using components from different suppliers. This so-called “handover” has been possible for several days in the laboratory under the real-world conditions of an actual mobile network. With this seamless transition, voice calls that begin as Voice over LTE (VoLTE) continue as conventional calls when leaving LTE coverage.
This represents progress on two fronts. Until now, almost all LTE smartphones have had to switch to older standards such as GSM or UMTS for calls, and VoLTE has been very rarely available. Telefónica is using the new technology in its Munich laboratory and even demonstrating handover to its 3G mobile network. This is particularly important when travelling by car. Without handover, VoLTE calls would drop as soon as the vehicle left LTE coverage. Another advantage is that VoLTE can provide customers with shorter call setup times and longer battery life.
For handover from LTE to a neighbouring UMTS cell, the engineers use the SRVCC standard (Single Radio Voice Call Continuity). Telefónica Germany is the first network operator worldwide to demonstrate SRVCC using components from several different suppliers, reflecting the real-world conditions of today’s mobile networks. Devices and network components from at least six manufacturers are used: Acme Packet, Ericsson, Huawei, Nokia Siemens Networks, Qualcomm and Sony Mobile.
Telefónica Germany is taking advantage of its infrastructure for mobile and fixed networks, which is based entirely on Internet Protocol (IP). Engineers are currently building a unified core network for fixed-line and mobile calls using a common IP Multimedia Subsystem (IMS). For the new VoLTE calls, Telefónica uses the same IMS core already used for the DSL calls of millions of customers. The same mobile subscriber database is also used as for the existing GSM and UMTS technologies.
“Telefónica Germany is once again demonstrating that we are among the pioneers. Our VoLTE technology is a world leader, and in Germany we are one of three providers using the powerful 800 MHz frequencies for LTE, the only frequencies capable of providing nationwide coverage with extremely fast mobile internet,” says René Schuster, CEO of Telefónica Germany. “With VoLTE and handover to GSM and UMTS, O2 customers will receive the highest possible voice quality and reliability for calls made with LTE smartphones.”
Telefónica will present its cutting-edge technologies this month at Mobile World Congress in Barcelona (25–28 February). It will demonstrate the implementation of voice services in LTE networks and explain its mobile communications strategy for the future.
