The ring generator terminals are usually under a little plastic guard or cardboard flap to keep nosy fingers out.
There is a modification to earlier 400D cards to make them ring on modern (metallic) circuits. If you're handy with a soldering iron, PM me for info on that.
My preference is either 400D ISS15, or ITT400E. I think (personal opinion here) the later Western Electric cards -especially the 400H- suck.
More often than not the polarity coming out of these fake phone line gizmos is backwards. I don't know why, it just seems really common in my experience. Try reversing them before you condemn the phone. If the TT dial still won't work, open up the phone and clean all the little contacts around the outside of the TT pad, and the ones on the bottom of it under the plastic cover. Those things are nearly indestructible. I've only ever had one go out of tune, and I twiddled the slugs in the coils on the back and got it right. Don't mess with those unless it is making tones and they aren't recognized. I wonder if the gizmo you're using has enough loop current to operate an older TT dial......
If you're only source of dial tone is the cell phone to pots adapter, that ground isn't as critical. I'm almost 99% sure the non-ringing is a result of those older 400D cards.
Like I said before, I have an honest-to-betsy copper line straight from the phone company central office (I asked a tech- nothing but a cross box between me and the CO) and my earlier 400D cards won't ring up. They used to, then one day they didn't. Checked my grounds, checked polarity, checked my sanity even. Something changed and those earlier cards just won't ring up. I put in the ISS15's and presto. I was back in business. They work fine with my grandstream VOIP adapters and my Obihai VOIP adapters, too.
