Multi-session Call in a Quintum D2400

I want to allow the calling party make a multi-session call in a Quintum D2400 by pressing the # key twice at any time during the call process and the Quintum should allow the calling party make a follow-on call. My Quintum doesnt allow this, the only time this is possible is when the called party disconnects the call first, the Tenor asks if the caller wants another call; the user can then press the designated key. Can someone advise how I can overcome this, it is particularly relevant when a customer misdials a destination number and wants to retry without having to hang up all start the call process all over from the beginning.