While you wait for answers, we may have found some information which could help you.
Click here for Bt Studio PhonesBeeping phone BT Studio 1100?
how to repair BT 3500 Studio phone base (Master) unit?
BT Studio 3500 base problem?
how can i fix a bt graphite 1100phone?
How do I connect my own answering machine?
BT Studio 1500 triple set?