Verify a phone number

Submits the SMS code from [Register a phone number](#operation/registerNumber). On success the account is created, an API key is issued, and a first phone number is provisioned — the response is identical to the sign-in outcome of [Verify a sign-up code](#operation/verifySignup). **The API key is returned only once — store it immediately.** If provisioning fails you receive a `502` and may retry this call with the same `registrationId`; the phone number stays verified, so no new code is needed. Note that `phoneNumber` in the response is the **Dial** number provisioned for the account, not the number you just verified.