[another_comment]

>>I’d argue that a reasonable network limitation with a minimal blast ratio is responsible.

I'm the OP and I agree. Across 3 Twilio phone numbers and I maybe make 4 voice calls and 10 texts a week. I've been doing this for 4 years or more.

>> For example, I use SIP over 5060 on Spectrum without issue.

As did I, until a week or so ago. Until I was cut off, without notice. I've been a Spectrum residential customer since the 1990s.