Not enough information and it seems to behave erratically. Not contacted Tech Support yet. Support URL in printed instructions is dead. Needs better instructions for VOIP POTS without cordless phones in home. I am somewhat allergic to radios. Literature does not tell what to expect when CPR Call blocker is disconnected for short period of time. It depends entirely on talk line battery. I need it to work and am not giving up. Tech support seems to be illusive.