great question. the main reason to use Sonar over twilio is that you'd have to essentially build our platform to be able to offer service like Magic. You need to be able to quickly send and receive text-messages through a web-UI (otherwise it becomes cumbersome to do it on a phone). we built that entire product already and it handle large volumes of messages from 10-digit numbers very well. with twilio, you just get the API.

also, we're built on (and love) twilio:)