This feature allows existing stable calls to be preserved when the branch gateway fails over to another server, or a survivable remote server, or returns to its main server. It is supported on all branch gateways. It applies to the failover and fallback of branch gateways to or from a survivable remote server and to or from a survivable core server.

During the failover/fallback process the bearer connection of stable calls are preserved. These include analog stations and trunks, DCP stations, digital trunks, IP stations using branch gateway resources, ISDN-PRI trunks, calls between gateways, IGAR, and previous connection-preserved calls.