The BT Synergy 4500 Twin comes with two hand sets and a built-in digital Answer Machine with up to 12 minutes recording time. Other features include a 255 name and number memory, three-way conferencing, 50 message capacity, SMS text messaging and much more. Features Two hand sets Answer machine with up to 12 minutes recording time 255 name and number memory Caller display 20 Calls list 3-Way conferencing 50 Message capacity SIM 4- Line blue back lit display