Ericsson has announced deployment of  3GPP CSFB in several networks in North America, Europe and the Asia Pacific region. Circuit Switched Fallback (CSFB) function enables voice and SMS services from operators’ existing 2G, 3G networks for LTE smartphones. According to company, it started  commercial deployment of CSFB technology during the second half of 2011. 

Circuit Switched Fallback network functionality means that mobile broadband data traffic is run over LTE, or HSPA when LTE coverage is not available, while voice and SMS services are provided using GSM or WCDMA circuit-switched networks.

CSFB is a software upgrade to operators’ core and radio networks, which include circuit-switched core (Mobile Softswitch Solution), Evolved Packet Core (Serving GPRS Support Node-Mobility Management Entity or SGSN-MME) and radio access (GSM, WCDMA and LTE).

VoLTE (Voice over LTE) is another IMS-based solution for voice services over LTE. Ericsson already offers a complete end-to-end solution portfolio for providing voice over LTE based on VoLTE (GSMA IR92) over all-IP LTE networks.