fax number
A company's recognized general fax number for initial or universal contact, distinct from an individual contact's fax.
The official fax number of a company is a fax number recognized and utilized by that company for purposes of universal or initial contact, and is generally the primary fax number made available to the public. This is distinguished from fax number(s) which belong to specific contact persons.
The number provides a general route to the company. Its usual public availability supports that role, but a fax number belonging to a particular employee is a different contact detail.
The purpose is general company communication by fax. A phone number describes telephone contact, while an email address provides the company's general electronic-mail contact.