In this configuration, the telephone registers to the server's Processor Ethernet Interface and the IP endpoint connects directly to the server Processor Ethernet. The connectivity path between the telephone and the server is:

Endpoint ⇔ IP network ⇔ Server

To discover connectivity failure, keep-alive messages are exchanged between the IP endpoint and the server. When the endpoint discovers that it no longer has communication with its primary gatekeeper, it looks at the next address on its list. If the next address is for a survivable remote server, then that server accepts the registration and begins call processing as long as media resources are available.

While the survivable server is not call preserving, the fail-over from primary gatekeeper to survivable server is an automatic process and does not require human intervention. The failback from a survivable server to a primary gatekeeper, however, is not currently automatic and requires a system reset on the survivable server. During the fallback to the primary gatekeeper, all calls are dropped with the exception of IP-to-IP calls.