• look into FIDO2 - not considering biometric auth for MVP 1
• user provides phone number, send some kind of code
  • twilio - API to send text messages - can we leverage?

steps better defined:

• the user enters the phone # into the app, 
• the app sends that to some TBD backend
• the backend creates a code with an expiration and sends it to the app via text message
• user enters text message code into the app
• app verifies code against backend