In this section:
SRVCC (Single Radio Voice Call Continuity) provides the ability to transition a voice call from the VoIP/IMS packet domain (LTE) to the legacy circuit domain. Variations of SRVCC are being standardized to support both GSM/UMTS and CDMA 1x circuit domains. For an operator with a legacy cellular network who wishes to deploy IMS/VoIP-based voice services in conjunction with the rollout of an LTE network, SRVCC offers VoIP subscribers with coverage over a much larger area than would typically be available during the rollout of a new network.
To configure SRVCC functionality, refer to Signaling - Global - CLI,
% set addressContext default zone ZONE_AS srvcc eatf <disabled | enabled>