Every article about this has gone into at least a cursory explanation that these weren't even really phones per se. They were basically hardware devices used to access AN0M. This had the double effect of 1) making the criminals feel like it was more secure because it wasn't "public" and 2) making it easier for the governments involved to make the software do whatever they needed it to do.

Basically, you'd buy them by the dozen, app preinstalled, sim and data probably optional.