BT 4000 Quad Digital Cordless Phones: With Big Buttons, Hearing Aid Compatibility & Extra Loud Volume The BT 4000 was designed with elderly users and mind; as such the handset has been shaped to make it easier to grip and is equipped with larger buttons, backlit display, and an amplify button for extra loud volume. Further benefits of this user-friendly set of home cordless phones include: Call Blocking, Hearing Aid Compatibility, and aDo not Disturbmode. Call blocking The call blocking features of the BT 4000 Quad enables users to prevent receiving calls from international and witheheld numbers, as well as up to 10 specific numbers that you can blacklist. And for guaranteed peace and quiet, there is aDo not Disturbfeature, which can be turned on to silence the ringer for all incoming calls except for VIP assigned contacts in the phonebook. User-friendly The phonebook has a memory for up to 100 name and numbers, which is automatically copied to all handsets so that it only ever