Lists your account's fax servers: each one a virtual fax line with its own number, notification email, retention and assigned users.

Who may call it: an API key with All permissions, for every fax server of your account. A Scoped key sees no fax servers: it gets [].

Use it: the fax_uuid of the fax server to send from is fax_server_id in POST /fax/send.

Response: an array of fax servers, [] when you have none.