Can't restrict video options

Hi folks,

I have successfully configured sip channels and able to call other users in my sip.conf. but not able to control video stream. what i want is that caller should be able to make audio or audio/video call and callee should be able to recognize somehow if he/she receives audio or video call. Letme make it clear I am able to receive audio/video calls but not able to recognize at receiver end if the call is audio or audio/video.

to explain my situation I am starting with sip.conf

I have videosupport = yes in sip.conf and various user define with

disallow=all
allow=ulaw
allow=h263p

also when I call I am able to recognize audio/video caller with ${CHANNEL(audionativeformat)} and ${CHANNEL(videonativeformat)} at run time in extensions.conf. and consequently want to place a call depending on these variables.

your help in this regard will be highly appreciated. please if you dont understand my problem i 'll elaborate further.

Regards