A:AnswerYou would need to find out from the Business Telephone installer to see what models are compatible with your ATT phone system.
The KXTGD563 is designed to be used as a residential telephone to the single-line telephone jack
(RJ11C) .
A:AnswerMine will hold a charge a day or two depending on how much I use it. Usally by day three its got one or two bars left. I love our phone. It does better than our last one.