What's the difference between CSFB & SRVCC

CSFB (Circuit Switched Fall Back) and SRVCC (Single Radio Voice Call Continuity) are two different technologies used in the mobile network for voice calls.

CSFB is a mechanism that enables LTE (Long-Term Evolution) networks to provide voice services using the legacy 2G/3G circuit-switched networks. When a user makes a voice call on an LTE network, the call is first routed to the 2G/3G network via CSFB. Once the call is established, the user's LTE connection is put on hold until the call ends. CSFB is used to ensure that voice services are available on LTE networks, even in areas where 2G/3G coverage is better than LTE.

SRVCC, on the other hand, is a technology that enables voice calls to be seamlessly transferred from an LTE network to a 2G/3G network without interrupting the call. When a user moves out of LTE coverage while on a voice call, SRVCC transfers the call to a 2G/3G network without any noticeable interruption to the user. SRVCC is used to ensure a smooth handover of voice calls between different network technologies.

In summary, CSFB is used to provide voice services on LTE networks using 2G/3G circuit-switched networks, while SRVCC is used to enable seamless handover of voice calls between LTE and 2G/3G networks.