The CS FallBack (CSFB) in EPS enables the provisioning of voice and other CS-domain services (e.g. CS UDI video, LCS, USSD) by reuse of CS infrastructure when the UE is served by E-UTRAN. A CSFB enabled terminal, connected to E-UTRAN may use GERAN or UTRAN to connect to the CS-domain.
Ericsson - Unlike previous 3GPP wireless technologies, LTE has no circuit-switched bearer to support voice, so carrying voice over LTE requires a migration to a voice over IP (VoIP) solution – commonly under the umbrella of IMS. Until this migration occurs, LTE-capable handsets need to revert to 2G or 3G for voice calls: an approach that is not ideal in the long term.
In this paper, Qualcomm and Ericsson share their insights on using circuit-switched fallback, (CSFB) as a solution to this challenge. Find out more about recent deployment experiences and extensive testing that has been conducted on the first phase of voice evolution between packet and circuit-switched networks.