The BT Duet 20 has a range of features including Call Waiting option, call indicator light, redial and secrecy buttons. It is also wall mountable and an ideal small gondola phone at an affordable price. Top Features Call waiting button Last number redial Secrecy button Ringer Hi/Low Hearing aid compatible Inductive Coupler Desk amp; Wall mountable Where described as VoIP compatible, this applies when used with the appropriate VoIP service such as BT39;s Broadband Talk service and hardware such as the BT Home Hub it is not a standalone voip phone