Mike, in my test setup, no tags are added to the To-header by the FreeSWITCH. The reason why I want to control it? Well, many phones uses the tag to relate an existing call to a NOTIFY message (send after the INVITE has been sent) with the same headers (and the same to-tag) as the INVITE. I’m not aware of how this functionality is described in the RFC, though.

My aim is the check if I can use the FreeSWITCH to replicate a function known in BroadWorks. In this system, there are a number of plug-ins and web-interfaces which are used to control the SIP phone: Answer, put on hold and resume. The plug-in controls the application server through a XML interface, which in turn sends the NOTIFY to the phone. Thus the phone can be controlled without connectivity between the PC and the phone. These three states are controlled by a Notify message sent from the application server. So it would be useful to find a way of sending a Notify message to the phone from the FreeSWITCH. Other NOTIFY messages could be used for other useful things such as resetting the phone.