Access token format
A Vivox access token is similar to a JSON Web Token (JWT), but with a limited set of claims (for example, vxi, f, iss, vxa, t, exp).
The Vivox access token is a string that uses the format header.payload.signature: three base64url-encoded parts that are separated by periods.
Important: Base64url encoding is not the same as Base64 encoding. For more information, see Access token terminology.