Third party doctrine is a known loophole to the surveillance state for getting around pesky privacy laws, and my gut instinct tells me this third party sms gateway is a goldmine for whatever prism has become these days. TOS/EULAs probably say they can do whatever they want with your data including sharing with third parties so they have a legal out because it's not just the corporations influencing congress via K-street, but because the military industrial congressional complex has a vested interest in providers not protecting our privacy, and will railroad any provider that tries to stand up to them (see: Quest).

Congress on both sides is utterly corrupt and unrepresentative and until America wakes up to that fact and stops playing the two-party game nothing will change. (duvergers law has many weaknesses)