SRVCC (Single Radio Voice Call Continuity)

Also known as: Single Radio Voice Call Continuity

SRVCC is a 3GPP procedure that hands an active VoLTE (or VoNR) voice call from the IMS/PS domain over LTE or NR to a legacy circuit-switched bearer on 2G/3G when packet-switched coverage is lost. It relies on the MME (or AMF) and an SRVCC-capable MSC, and the handover reuses SS7/MAP toward the CS core. SRVCC creates a security transition point where PS-domain protections give way to CS-domain assumptions, and is often abused via SS7 signalling to intercept or redirect voice.

Categories: Radio Access NetworkCore NetworkSignaling

SRVCC in context

The radio access network is where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations and downgrade attacks; defenses rest on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core carries subscriber sessions, mobility and policy. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF.

To place SRVCC in the wider telecom-security picture, review 5G SA, AMF, Base Station (BS), Capacity Planning, CAPEX and CSCF — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.