This is very easy and cheap to implement with Asterisk and a no-name VoIP provider. I've done some messing around with phones in the past and I would expect tha

This is very easy and cheap to implement with Asterisk and a no-name VoIP provider. I've done some messing around with phones in the past and I would expect that Twilio has little/no effect on this space -- the barriers to being spammy with Twilio are higher than with Asterisk and another VoIP provider.