Survivable Branch Appliances

Although not necessarily a feature of Lync Server itself, a concept that is now possible via Lync Server is that of a Survivable Branch Appliance (SBA). Several vendors have announced appliances that run Lync Server. These appliances allow for simplified implementation of dial plans and offer localized services with the capability for a centralized data center to take over in the case of a localized failure of the appliance. The appliances integrate a PSTN gateway, Mediation Server, and Registrar. Built in various formats by companies like Audiocodes, Dialogic, Ferrari, HP, and NET, these devices provide many services such as the capability to hand control of local calls back and forth between the appliance and a remote data center, enabling one to serve as a backup for the other for branch user calls.

When configured in this manner, the following services are available in the event of a WAN outage:

• PSTN and other voice services

• Hold, retrieve, transfer

• Authentication and authorization

• Call forward, simul-ring, boss-admin, team-call, and do-not-disturb routing

• Call detail records

• Intrasite IM and A/V

• PSTN audio conferencing

The following services are unavailable in a WAN outage:

• IM/V/W conferencing

• Presence

• Update call forwarding setting

• Response group service