If a user dials in with i.e. his cell phone to a OCS conference, and is not using CWA, how can the external user mute and unmute his line, if the phone does not offer a mute/unmute button. Is there any DTMF capability (*6, #6 i.e.) available to mute/unmute the line?
Ask your cell phone provider how to mute the phone. You didn't mention the cell phone model, but don't virtually all of them have their own mute capability?