While you wait for answers, we may have found some information which could help you.
Click here for Cordless Phone Telstra Problem
Telstra 7100A, "Not Registered"?
How to fix Telstra 8950 answering machine?
My cordless phone says Base 1 (Telstra 7100) ?
How can I mend my Telstra 12250 cordless phone?
Telstra cordless 6100a Won't make calls?
How can I add a handset to telstra v580a?