I have a Twilio mobile number that has both voice and SMS functionality. I am able to make and receive calls in Zoiper, but I don't know how to set it up so I can also send/receive SMS. There are no guides on how to do this. How do I set this up?
Twilio developer evangelist here.
Twilio doesn't support SMS over SIP, only via the REST API (outbound) and webhooks (inbound). Twilio doesn't support SMS via SIP SIMPLE (as the Zoiper docs mention) so you cannot directly set up sending and receiving SMS messages via Twilio through Zoiper.