Because LTE can only provide packet services

there is a long-term demand for voice and short message service. For the LTE

the realization of voice and short message service in several ways were in-depth research and analysis

especially in the presence of CSFB and IMS voice

the reconstruction of EPC core network

which focuses on the CSFB implementation process

Vo LTE-IMS Voice implementation and e SRVCC switching technology.