I am running in to an issue with Yealink phones not fully re-registering to the backup server after a WAN failover on the primary server. The way our servers are set up is their is a primary server in one location and a backup server that is created from a backup of the primary in another location. We are using DNS fail-over so when the primary goes down the phones will automatically re-register to the backup and when the primary is back up the phones will roll back. The issue is that the phones take about 30-45 minutes to become available for inbound calls but the DNS service we are using propagates the updated lookup in about 5 minutes. When placing outbound calls after the DNS has changed outbound calls go out through the backup. Inbound calls ring in to the system but the phones take the 30-45 minutes to show up in the system and when they do the inbound calls start routing to the phones. Wanted to see if anyone had run in to anything similar. Could still be a phone manufacturer issue but it seems odd that the phone is sending outbound calls out through the proper server but takes so long to register to the phone system for inbound calls. Note: I watched the phones during fail-over and they do not appear to be dropping registration during the time it takes to fully register to the backup.