I'm not sure I understand what you're trying to do, but here goes. When you pick-up the phone that's supposed to ring, does the clicking stop? Also, the modem that is dialing out, is looking for another modem. I only see one in the equation so far. Was the KX-TA 624 new out of the box? If you have two phones, try the same set-up to make sure that the switch programming isn't causing a problem. This would only be a problem with a used switch, that may have had some custom programming in it, ie, station call forwarding, etc.
