How can I customize the phone number from which Mixpanel sends SMS messages?

Mixpanel partners with Twilio to send SMS messages; Twilio receives your users’ phone numbers from Mixpanel and sends your messages to the numbers provided, regardless of what country those phone numbers are from.

If you would like to send all of your SMS messages through your own Twilio account, email support@mixpanel.com and ask for 100% of SMS messages to be sent through Twilio. Once this flag is enabled, you can customize the sending phone number and the unsubscribe options within Twilio's settings.