[dooglius]

Disclaimer: IANAL

As far as telephony is concerned (things like SMS are a different story), a phone provider cannot legally do this, even if you signed some ToS agreement. According to the FCC, phone providers, including voip providers, have legal requirements around when they are allowed to terminate service: https://www.fcc.gov/consumers/guides/when-your-telephone-com...

[meepmorp]

The page you link to says that this doesn’t apply to mobile providers in general.

[dooglius]

I was under the impression that voip is not considered "wireless" but I could be mistaken there.

[meepmorp]

I get the impression those protections are for residential phone service, not the kind of stuff twilio does. Leaving that aside, though, SMS (at issue here) is definitely in the wireless realm, even if the messages come from an API call rather than a mobile device's radio.