(n.) Using an IP-based network, especially the Internet, to transmit faxes. IP faxing is similar to Internet telephony, but it's optimized for transmitting fax data. IP faxing generally works by sending fax data over the Internet to strategically placed fax servers. Once a fax arrives at the server closest to its final destination, it's transferred onto normal telephone lines and transmitted like a normal fax. Because the data is transmitted over the Internet for most of its journey, the total cost of transmission is much less than if it traveled over long-distance telephone lines like conventional faxes.
There are many products that enable large companies to set up IP faxing servers at their own office locations. There are also national and international IP faxing services that allow companies and individuals to send faxes over their IP faxing networks for a fee.