Call Preservation and Connection Preservation during LAN failure

When near-end failure is detected, the SIP signaling group state changes to the Out-of-service state. The SIP trunk in the trunk group is in a deactivated state and cannot be used either for incoming or outgoing calls. Stable or active calls on the SIP trunk are not dropped and are kept in the In-service/active state. When the active connection is dropped, SIP trunk changes to the Out-of-service state. When far-end failure is detected, the SIP signaling group state changes to the Far-end-bypass state. Stable or active calls are not dropped, and the SIP trunk changes to the pending-busyout state. When the active connection is dropped, the SIP trunk status changes to the Out-Of-Serivce/FarEnd-idle state.

Call Preservation and Connection Preservation when LAN connectivity is revived

When the near-end failure ends, the SIP signaling group state changes to the In-service/active state. Stable or active calls on the SIP-trunk are kept in the In-service/active state. When the far-end failure ends, the SIP signaling group state changes to the In-service/active state. The state of Stable or active calls on the SIP trunk changes from pending-busyout to the In-service/active state.

The Connection Preservation mechanism also works with DCP and H.323 telephones.