While you wait for answers, we may have found some information which could help you.
Click here for Bt Dial Phonebt 1100 twin need to replace broken 2nd handset?
How do I connect my own answering machine?
Permanent engaged tone on BT Studio 1100 handset?
Beeping phone BT Studio 1100?
Bt 3500 cordless tel/answerphone?
How can i show calls made to my phone?