Account
Details of the account your API key belongs to, and the sender IDs it can send from.
A sender ID is what a recipient sees a message as coming from: a dedicated number, a verified
phone number, an alphanumeric name, or SHARED_NUMBER for the shared pool. Use the sender ID
endpoints to find a valid from before sending. Pass a recipient's number to get only the
sender IDs that are valid for that recipient's country.