Validate request

1. 1. Validate request using JSON schema
      
      1. In case validation failed - generate 422 error

Authorize user

1. 1. Verify the validity of access token
   2. Check user scopes in order to perform this action
      1. In case error - generate 401 response

Generate verification code

1. 1. Generate verification code using basic random (default) function or time-based algorithm
   2. Verification code format - digits only ^[1-9][0-9]*$
   3. Verification code length - configuration parameter (default = 4)
   4. Verification code expiration period - configuration parameter (default = 15 min)
   5. Set expiration period using configuration parameter

Deactivate active verification code

1. 1. Search active verification code(s) for this phone number
   2. If found - change status to INACTIVE

Save verification code

1. 1. Save generated verification code to DB

Generate SMS text 

1. 1. call Man method - templates rendering service.

Send SMS

1. 1. Send SMS via API - currently Twilio. TBD - Postboy
   2. Message template - configuration parameter