try www.user-guides.co.uk
To use Caller Display you must first subscribe to the service from you service provider [eg: BT] and there may be a quarterly charge for this service. It cannot be switched on at the telephone.
Telephone system works on low voltage.
As long as no part of your telephone system including answer machine is plugged into a 13amp socket (uk) and fed to system via transformer then fine ordinary batteries are ok.
bob, March 2011