- Make sure you are using the latest firmware version for your Snom phone.
- Make sure the SIP identities are configured correctly and can register with the Registrar.
- Revise the configuration of the following settings:
- user_failover_identity - The index of the failover Identity
- retry_after_failed_register - Number of seconds after a failed registration the Primary will try to re-register
- active_line - The Primary Identity
- user_expiry - The proposed expiry time of the registration in seconds for line x. Upon expiration of the registration, the phone will send a fresh re-registration request.
- sip_health_check - Enables/Disables the status polling of primary server if the phone has been failed over to the backup server
session_timer - Session Timer for calls (try setting to 1800 seconds)
Be sure not to use Identity 1 as the Primary with Identity 12 as the failover Identity. There is a known issue (SCPP-6267 - Failover not working between Identity 1 and 12)
Retry and test the failover.