From MSNPiki

RNG

The RNG command is sent to you from the notification server whenever you have been invited into a switchboard by another principal using the CAL command.

RNG sessid address authtype ticket invitepassport invitename\r\n

• sessid : The session ID of the switchboard you are being invited to. You will need this when identifying using the ANS command.
• address : Address to the switchboard, given in IP:Port format, port has never been anything but 1863 - this may change in later versions.
• authtype : This defines the type of switchboard authentication you will need. Nothing but CKI has been seen here, and is what we describe.
• ticket : The switchboard's authentication ticket. You will need this when identifying using the ANS command.
• invitepassport : Passport account of the principal who added you to the switchboard session
• invitename : URL encoded MSN friendly name of the person who invited you. This is not always syncronized with what the notification server says - accurate information is given by the notification server.