is this just like anotherservicetwilioruined.example.com/api/doesthispersonhaveanaccount?phone=+12012000000 and then the service says 'yeah that number has an

is this just like anotherservicetwilioruined.example.com/api/doesthispersonhaveanaccount?phone=+12012000000 and then the service says 'yeah that number has an account' (and nothing else?)? then whomever repeats that for every possible phone number? or... more than that?