>In the end this entanglement mixes legitimate calls with malicious ones by the time they reach the destination (final) carrier, making it impossible for them t

>In the end this entanglement mixes legitimate calls with malicious ones by the time they reach the destination (final) carrier, making it impossible for them to drop malicious calls without impacting a lot of legitimate usage. No, I did not say "drop calls", I said drop the source. If Twilio got blocked on T-Mobile it would found which re-seller is responsible in no time. If it was their hacked server - they, again, would have found it and patched. It's no different from e-mail spam in early 2000s - all e-mail from a server sending spam would have been blocked, including legitimate e-mail.