BT Graphite Cordless Phones. With the BT Graphite 2100 and BT Graphite 2500 Ranges of Cordless Telephones you have complete communications solutions for home or office with call transfer, caller display and intercom between handsets. They have new added features to BT Graphite 2100 and Graphite 2500, introducing clearer LCD screens as well as larger buttons on the handset for ease of use.