The Dialogic 4030DTISBA gateways are integrated systems that can provide both local PSTN and voice endpoint connectivity at a branch office premise as well as base-level voice service continuity in the event that the corporate WAN becomes unavailable. The DMG4030DTISBA are standard rack-mount servers running the Windows Server 2008 R2 operating system. They support the Survivable Branch Appliance function that is part of the Microsoft Lync Server 2010 for unified communications. The Survivable Branch Appliance function allows branch offices to work effectively even if the WAN connection to the central site is lost. The ability to make voice calls, use email, and hold audio conferences continues to be available.