http://support.microsoft.com/kb/2027572
Network ports
The following table lists the network ports that Windows Live Messenger must use for specific features to work.
Feature Port
Sign in to the Messenger service TCP 80, 443, 1863
Network detection TCP 7001
UDP 9, 7001
Voice and video (V/V) Messenger VOIP servers for call establishment of voice and video services listen on ports 1863 and 443.
Media flows directly between both endpoints (either directly or through a relay server) over UDP or TCP by using any available port.
File transfer TCP 443, 1863
TCP/UDP 1025 - 65535
Whiteboard and application sharing TCP 1503
Remote Assistance TCP 3389
TCP/UDP 49152 - 65535
Games TCP 80, 443, 1863
TCP/UDP 1025 - 65535离线