Just to add to the sibling comment, Twilio isn't the problem either. The problem is that SS7 (the PSTN control protocol) allows you to set your caller ID to wh

Just to add to the sibling comment, Twilio isn't the problem either. The problem is that SS7 (the PSTN control protocol) allows you to set your caller ID to whatever you want. So any bulk sender, VoIP provider, medium+ business with 2+ phone lines, etc, can either spam you with random phone numbers or sell access to spammers to do the same. "STIR/SHAKEN" is something to research to see what the government/telephone industry plans to do to stop the problem.