Recently I was working on a customer’s global roll-out of Lync 2013 and we were designing how their branch sites would work from a voice perspective. Each branch site would have an SBA for voice connectivity to the legacy PBX/ISDN and for survivability, but we also had to map out how voice mail would work in the event of WAN failure.

Here’s how things would look like in a normal scenario with the WAN up:

With the Exchange Unified Messaging servers being in the central data centre along with the main Front End pool, this meant we needed to configure voice mail survivability. This is a feature Lync 2013 provides out of the box, but not one I knew a lot about or how to configure it. Outlined at the bottom of the TechNet Library article Branch-Site Resiliency Requirements, we can determine how Lync still provides voice mail deposit and retrieval in the event that the SBA cannot contact the central Exchange UM server/s. Continue reading →