A fax number, or facsimile number, is a unique identifier assigned to a telecommunications device capable of sending and receiving faxes. Like a phone number, a fax number is a combination of digits that identifies a specific machine connected to a telephone line.
Using a fax number, one can transmit and receive documents via telephone lines in digital form. Fax remains a relevant method of communication, especially for transmitting physical documents such as contracts, purchase orders, and invoices. It offers benefits like security, legal validity, and cost-effectiveness. Historically, the development of digital fax machines in the 1980s revolutionized business communication by enabling electronic document transmission.