Another UX idea: you have a three-step process: sign up -> add credits -> call anywhere. IMO you could simplify this to two-step: add credits -> call anywhere.

Another UX idea: you have a three-step process: sign up -> add credits -> call anywhere. IMO you could simplify this to two-step: add credits -> call anywhere. The key insight is that adding credits (the first time) _is_ or _includes_ signup -- you'll create and validate someone's identity or payment there. If you make it require minimal enough information (email address or phone for a verification code) it could be very smooth.