MSN Messenger Protocol
Many Messenger-related protocols are called using invitations. For a discussion of the invitation protocol itself, click here. This page describes the values of fields needed to negotiate specific protocols. For protocols that require you to send "IP-Address: IP:port" instead of just "IP-Address: IP", the description will specify an "IP-Address port".
Submitting Invitation Types
If you have information on an invitation type that is not on this page, please submit it to us. Currently, we do not have a nice system for submitting invitation types. Until one is setup, please submit your entry as a reply to the forum thread Submit All Known Invitation Types (thread ID 4042).
Application Sharing is some kind of SOAP-over-HTTP application we don't understand. For some reason known only to Microsoft, an IP address without a port is sent in the first ACCEPT message, then the same IP address is sent in the Context message, this time with a port.
Baldur's Gate 2
Baldur's Gate 2 (which is misspelled as "Baulder's Gate2" in the official client's Application-Name) is a roleplaying game from Interplay Entertainment. The port is not specified in the "IP-Address" field, but it is always TCP port 47624.
MechWarrior Mercenaries is an FPS game from Microsoft.
MS NetMeeting is a voice-chat and shared whiteboard program from Microsoft. NetMeeting uses the H.323 and T.120 standards, so (despite the name) you can use any program which conforms to these standards. For example, GnomeMeeting and ohphone support H.323.
The Rendezvous Protocol specification hints at "NetMeeting 3.01", which has a different GUID, but seems otherwise identical.
Windows XP allows you to request "Remote Assistance" from through the official client. The protocol used by XP's remote assistance package is RDP 5.1. At the time of writing, no independent implementations of this protocol were known, but the RDesktop project are apparently working on it. The various context data sent in a remote-assistance invitation are not yet properly understood. Remote Assistance was discussed in this phorum thread, but hasn't been fully deciphered.
Voice and video conversation
"Voice conversation" and "video conversation" negotiate an SIP (Session Initiation Protocol) session. The official client uses a built-in SIP program, but any SIP-capable program (such as LinPhone) will do. SIP is defined in RFC 3261. The audio capability is referred to as "SIP_A", while the video capability is "SIP_V". See thread 6131 for a discussion of voice chat.
Webcam support (which is distinct from video chat) uses the "Real Time Protocol" defined in RFC 1889. The official doesn't put curly brackets around the Application GUID for webcam support.
Whiteboard is some kind of SOAP-over-HTTP application we don't understand. For some reason known only to Microsoft, an IP address without a port is sent in the first ACCEPT message, then the same IP address is sent in the Context message, this time with a port.