The INFO method is used by a user agent to SEND CALL signaling information to another user agent with which it has an established media session. This is different from a re-INVITE since it does not change the media CHARACTERISTICS of the call. The request is end-to-end, and is never initiated by proxies. A PROXY will always forward an INFO request—it is up to the UAS to check to see if the dialog is valid. INFO requests for unknown dialogs receive a 481 Transaction/Dialog Does Not Exist response.

The INFO method is used by a user agent to send call signaling information to another user agent with which it has an established media session. This is different from a re-INVITE since it does not change the media characteristics of the call. The request is end-to-end, and is never initiated by proxies. A proxy will always forward an INFO request—it is up to the UAS to check to see if the dialog is valid. INFO requests for unknown dialogs receive a 481 Transaction/Dialog Does Not Exist response.