I've had this issue with voip devices. You can try cleaning the contacts around the sides and on the back of the dial. Just use a non-glossy business card, put it between the contacts and hold a button down to activate the contacts. Then drag the business card around a little. It certainly can't hurt anything. I've had a few with the same issue, works on copper, hit and miss on voip, and the only solution was to re-tune or replace the dial. Try cleaning it first. If that doesn't help, you're looking at re-tuning or replacing the dial. I've had about a 50% success rate re-tuning dials. Most of the time the slugs are stuck and won't turn. Usually all it takes is a tiny tweak to get it working again. Before you attempt this and risk making the dial completely useless, make sure it's not an issue of the magic jack not providing enough current to actually power the dial. This might be hard to test... One other thing you can do, pick up the suspect phone and a known working phone on the same line (use your copper line for this) and dial your magic jack number or your cell phone or something else you can answer and get a quiet line. Compare the sounds from the known good dial to the suspect dial. You should especially be able to notice a problem when you beat the tones together. If they are the same, all you'll hear is the tone, if one is out, you'll hear the warble of it going in and out of phase. I suspect it's only out a few hertz. Copper lines are a bit more tolerant than the voip adapters usually are. If you were using an unlocked adapter (magic jack uses locked adapters) you could probably set the tone detection a little looser and it would probably be fine.
Dials are around to be had. Unfortunately the 2565's have extra leads for the speakerphone, so the dials are a little rarer. I have a box of TT pads somewhere, but I'm pretty sure they aren't speakerphone compatible. I'll look in the next few days and see if I have one.
