An engineer is developing a new SRST configuration for a branch router using PRI for PSTN access. The engineer is developing a test plan for SRST using this new H.323 gateway. How does the engineer…

Dialing another internal extension after the WAN is down tests IP phone re-registration under SRST but does not validate H.323 gateway call routing or call preservation.

Dialing an extension at a remote site when the WAN is down is not possible because the inter-site path traverses the failed WAN link.

Establishing a live call through the H.323 gateway and then severing the WAN link directly simulates a production failover event, forcing the SRST router to take over H.323 call signaling from CUCM and testing whether the active call survives the transition. This method validates both the H.323 re-homing behavior and the call preservation capability of the SRST gateway simultaneously. It is the definitive test because it exercises the exact failover path - an active H.323 session handed off to the local SRST router when CUCM becomes unreachable.

Placing a call on hold and retrieving it tests supplementary hold functionality on the gateway, not H.323 signaling behavior during a failover event.

Placing new outbound calls after the WAN fails tests the SRST dial plan and PSTN reachability, but does not validate that in-progress H.323 calls are preserved through failover.