Sends an info packet with a sipfrag. If the phone supports it will show message on the display.
Tested on a soundpoint 670 running sip 3.0.4. Works fine on Polycom. Display text shows up in 'placed calls', seems to be intended for sending the name of the called party to the caller.
Can send only one message to the display before answer. After call is answered, the display message can be updated at will. Call list record will show last message sent.
Call hangs up when it gets the message.