Lync Server 2010 introduces Location Information Service (LIS) to provide location information to Lync clients, primarily to support E.911. However even without LIS the client itself has a mechanism to store location information and correlate it to the network you are connected to. As a user you can define a location as “Home”, “Hotel X” or “Customer Y” and Lync 2010 will store the information and present the correct location next time you connect to the same network. Typically home or public network uses one of the IPv4 private address ranges defined in RFC 1918, i.e. 192.168.1.x, but how is Lync 2010 able to distinguish the network 192.168.1.x in my home from the network 192.168.1.x in “Hotel X”?

When you store a location Lync 2010 will store the civic address information you provide together with a piece of network information uniquely describing the location. The piece of network information it stores is the MAC address of the default gateway or the MAC address of the wireless access point you are connected to. Being MAC addresses they are globally unique and in this way the client can distinguish between different networks using the same IP range.

To see the MAC address of your default gateway use ipconfig to get the IP address of the default gateway and then do arp –a to get the MAC address corresponding to the IP address.

To see the MAC address of the wireless access point you are connected to use the command netsh wlan show networks mode=bssid and look for the SSID of the wireless network and then the line with BSSID.