Hello,
I had read that PAP2T is not certified with CUCM yet. I found that some PAP2T doesn't register one of the two lines but, with some patience + some add/delete operations + power cycle the PAP2T, you can achieve it. I have some PAP2T with CUCM 7.x and a bunch with CUCM 6.1.3. So far, this devices are working relatively fine.
Hope it helps, please rate if it does.
Kind regards,
- Adrian.