BT Big Button 4600 Cordless Telephone with Answer Machine with premium nuisance call blocking powered by trueCall's award winning technology, allows you to block 100% of nuisance calls. The big buttons make dialling and keying in information simple, whilst the inbuilt answer machine will record all your messages, ideal if you can't take the call. (You must subscribe to a Caller Display service from your network provider to block nuisance calls and use visual voicemail. Charges may apply. ). Avoid nuisance and unwanted calls with multi-award winning truecall blocking technology - type 3 call blocking - blocks a specific list of numbers and has either a virtual answering assistant or audible name announcment. 1.8" backlit display screen, hearing aid compatible, "hot k.