Telstra 7100A, "Not Registered"?

If anyone ever wants to know how to register a Telstra 7100 handset to a base this is how you do it (it's not in the manual)... this is from trial and error.

Press and hold the Page button on the base down until it emits a long beep.
Go Menu, Register, "REG BASE"
Press the number 1 key
Press the Page button on the base station
The handset will ask for a PIN – enter 0000

That should be it.

try this
May 2014