BT 4600 Twin Digital Cordless Phones with Big Buttons & Advanced Call Blocker. A practical set of digital cordless phones for the home with Nuisance Call Blocking powered by Truecall the BT 4600 Twin helps you protect your home from unwanted sales calls. Each handset features extra-large buttons for ease of use and is capable of providing reliable range of up to 50 metres indoors and 300 metres outdoors you can enjoy calls in outstanding clarity throughout your home.. Call blocking made easy. The BT 4600 Twin comes with BTs multi-award winning call blocking technology powered by TrueCall for complete protection against nuisance callers. Now with a dedicated call-block key you can instantly block numbers from incoming callers (up to 1,000 numbers can be added to the blocked call list). And with the Premium Call Blocking feature youll never have to speak to another cold caller again as the phone will make unknown callers announce their name and play it back to you so you can decide whe