Abstract: A telephone trouble isolator comprising a hollow container adapted to receive a plurality of external and internal telephone lines from a telephone branch exchange and internal telephone lines resident in a home or business; a trouble isolator circuit disposed within the hollow container, the isolator circuit including a plurality of telephone activation circuits connected in parallel, the activation circuits adapted to be connected in parallel with the external phone lines, each activation circuit having a switch connected in series with an internal telephone line terminal, whereby an internal telephone line connected to the internal telephone line terminal may be activated or deactivated with the switch, and a telephone test jack connected in parallel with the activation circuits and adapted to be connected in parallel with external phone lines, the test jack adapted to receive a test telephone such that a user may monitor dial tones on the lines, with the isolator circuit adapted to be energized by an exte