> T-Mobile would have to white list the phone for it to work. This is a real pain, especially since I have been needing to field some really important calls lately.

I guess, there is nothing you can do if your provider bans your hardware.

> it seems like it drops to 2g for the call

This means, the poster is using an outdated modem firmware, which should be upgraded by contacting Purism (AFAIK Purism isn't allowed to freely distribute it).

Calls seem to work fine for me.