update_type: "editServer" replaces the fax server wholesale instead of merging: the user assignments and the email-to-fax list are cleared and rebuilt from users and emails_to_fax, so leaving either one out removes everyone. Changing caller_id_number detaches the old number, attaches the new one, rewrites that number's inbound routing and records both changes in the numbers' histories. update_type: "logo" is the narrow alternative that touches only the coversheet logo. Requires an API key with the Admin role; the steps are not transactional, and an id that does not exist fails as a server error rather than a 404.