SIP Messages
============

@2007 by Antonio Gallo (AGX) - www.badpenguin.org

SIP is a very wide standard, between his many specs its allow instant 
and non-instant messages to be exchanged between SIP clients.

The original SendText() application released with Asterisk 1.2.0 was 
just a generic implementation of sending text between different
technologies: for instance an ISDN phone can display things like a
SIP phone.

With CallWeaver 1.2 i've introduced a SIP specific application called
SIPOSD(). This application can display messages onto the telephone
screen during a call (OSD = On Screen Display).

The application requires that the channel has to be already answered.

It has been tested sucessfully with:
- GrandStream GXP 2000
- Snom 300, 320, 360

This is an example of dialplan that i use to test if a new SIP client
support the MESSAGE feature:
	exten => *9004,1,Answer
	exten => *9004,n,Playback(beep)
	exten => *9004,n,SIPOSD(This is a SIP OSD message)
	exten => *9004,n,Wait(3)
	; this will clear the screen
	exten => *9004,n,Playback(beep)
	exten => *9004,n,SIPOSD
	exten => *9004,n,Wait(3)
	exten => *9004,n,Proc(fine)

Example of its use is to display the user progress information or
wich outgoing line is it going to use for his calls. You can find
more funny use for this yourself.

If you want to send a message to the phone without Answering the call
or without using the dialplan or the PBX there is an external utility
that does the job: "sipsak". This utility has nothing to do with SIPOSD
and its not part of the CallWeaver project but you can find it usefull.