"FreedomPop pays Sprint and AT&T based on customer usage. The two big carriers can see what websites FreedomPop users are checking out, but neither they nor FreedomPop can record or monitor calls as long as only FreedomPop users are participants. "
I use Hangouts which means FreedomPop is monitoring all my calls. Gotta decide if my free service is worth this! In a way, it will be good if FPop goes the way of RingPlus - they will save me the trouble of deciding!
Just thinking this through quickly, but I think your concern with FreedomPop may be backwards: if your concern is the possibility that your calls may be monitored, FreedomPop may be an especially good choice-- possibly safer than any of the standard carriers.
The key part is that if either end of the conversation is not a FreedomPop subscriber, the call can possibly be monitored-- I don't think anyone's claiming this happens as a matter of course.. This isn't a risk of FreedomPop, it's an acknowledgement that nearly every carrier can monitor your calls & will do so if required by government bodies, while FreedomPop-to-FreedomPop cannot.
I believe it's been noted that FreedomPop uses a customized variant of CPSimple, which is apparently very difficult to monitor by any outside agency, or even by CPSimple itself.
From an article about possible monitoring of your communications, and possible data-mining:
" So encryption is really more important here than which service you use. CSipSimple is a VoIP app with much more intense security--it sets up its own container for the call, while apparently not interfering with the actual content of the call at all."