It should respond to the ##88 command which is the initial login password to the unit.I would try a different phone, which is the usual cause of the non-responsive unit. Somehow, the tones are being changed on your phone so the receiving end does not understand the commands. This could also be happening at the location if you have something else also using the phone line. For instance, a Fax or multiple phones.Some cell phones allow you to increase the duration of the DTMF tones. Android phones allow this. By increase the duration of the tone, you are increasing the chances of the DTMF tones being interpreted correctly at the receiving end.Also make sure the phone line from the wall is plugged into the LINE port on the side of the unit, not the DEVICE port which is reserved for a telephone or other device.