Survivable Remote sites include a Survivable Remote Session Manager and Survivable Remote Communication Manager that is either a Feature Server or an Evolution Server, depending on the main Communication Manager to which it is connected. SIP phones simultaneously register to the main Session Manager, a backup main Session Manager, and the Survivable Remote Session Manager. During a WAN outage that removes the communication path between phones and the associated Session Manager, the phones failover to the Survivable Remote Session Manager and the Survivable Remote Communication Manager.