Messenger 7 application sharing SIP timed out

[Wilts]

I cannot get application sharing to work in messenger 7. I always get the
message SIP timed out. All other functions in messenger work (file sharing,
audio, video etc). UPnP is enabled on the routers at each end of the comms.
Both networks are running MS SBS 2003 with XP workstations.

Any ideas?

Ian

 

[Wilts]

Further testing shows that desktops plugged directly into the router work
fine. However, desktops that operate through the server (i.e. server has two
network cards and acts like a router) cannot share applications. I assume
there is a server firewall/service change that I need to make. Do anyone
know what that might be, does UPnP work through a server?

Ian