Circuit-Switch Fallback (CSFB) is a mechanism currently used to provide voice services to LTE devices, by signalling an LTE device to "fall back" to the 2/3G network to make or receive a voice call. It has been used in LTE FDD devices and networks, but now Ericsson has said it has become the first to demonstrate voice fallback for LTE TDD (TD-LTE) .
The demo, carried out at the PT Expo in Beijing on Ericsson LTE TDD network (RBS 6000 base station) and a Qualcomm chipset, could speed up the development of dual mode TDD-FDD devices, Ericsson said. That would allow operators to offer voice services to both TDD and FDD modes, making the best use of the spectrum they have available, and driving economies of scale in the TD-LTE device market.
Serge Willenegger, Vice President Product Management at Qualcomm, said, “We are pleased to be part of this important industry milestone, having worked very closely with Ericsson. The efficient support of voice and messaging services in LTE multimode smartphone platforms is instrumental in driving device economies of scale in key LTE TDD regions such as China.”
Per Narvinger, Head of Product Line LTE, Business Unit Networks, Ericsson said, “For carriers and service providers, available frequency bands for communication services are limited and precious resources. Multi-mode networks and devices that make the best use of these resources are crucial for providers to be able to stay competitive and serve consumers in the best way. LTE TDD, which uses un-paired spectrum, is one of the important technologies to support rapid uptake of smartphones and data traffic growth in operator networks.”