A:AnswerIf it is an extension of another phone just take the new one and set it on the base of the main phone. It will update everything to the new phone. It sets the time, date, and all of the contacts in your main phone. I don't remember how long I left it setting on the main base, but it wasn't a real long time, I do remember that.
A:AnswerMars - No, the VTech CS6709 is only compatible with the following base models: CS6829, CS6585, CS6719, CS6728, CS6729 and CS6759.
Thank you,
-VTech Support