When viewing "Network" in active directory not all users pc show from each office. Some do some don't. I made sure all pc/laptops have turned on their ability to be see (the prompt you get in Windows 7, the first time you go into "network".
We use DHCP addressing for all three of our office with one DHCP server in 1 office and the other two DHCP is handled by their Cisco router and the other office DHCP is handled by the Mitel PBX, MCP 300.
Does wins come into play in this? I'm not sure