Values accepted for Alphabet Type in the Otp API.

Prefer the documented atoms returned by values/0. The type also accepts strings so a newer server value can be preserved by an older SDK instead of failing during decoding.

Initiates, verifies, and inspects one-time passcode transactions.

OTP delivery and verification are separate steps. Initiation returning successfully means the transaction was accepted, not that the recipient received or verified the code. Keep the returned transaction ID and submit the user-provided code through verify/3.