Fax Over Internet Protocol (FoIP)

Last Updated: August 18, 2011

Definition - What does Fax Over Internet Protocol (FoIP) mean?

Fax over Internet Protocol (FoIP) is a fax technology that uses digital packets for Internet transfer. Two key FoIP approaches are store forward and real time. Store forward uses email to transfer data from a source to destination. Real-time is similar to traditional phone line faxing, where IP data packets transfer from source to destination via high-level IP, such as Transmission Control Protocol (TCP) or User Datagram Protocol (UDP). FoIP is also known as IP faxing.

Techopedia explains Fax Over Internet Protocol (FoIP)

FoIP standards include:

IP packet data that use routers for decoding.
Data transmitted via phone, IP gateway or fax modem.
Configurations, including traditional G3 to G3 fax machine, fax-equipped personal computer (PC) to G3, IP fax machine to G3 and IP fax machine to IP.

FoIP implementation follows a series of sequential steps, as follows:

Sender transmits signals to receiver.
Fax session is initiated.
Receiver responds.
Sender establishes a connection.
Faxing begins.
Each machine exchanges digital control signals that describe page color, size and supported [n1] [n2] data compression, etc. G3 machines use the T.30 protocol to encode digital data as analog and decode analog data as digital.
Sender scans data and produces a digital bit series represented by black and white converted analog pages.
Receiver decodes the data, reads each bit and prints data based on bit instructions. The T.38 protocol, used for image data compression and integration (G3), is a real-time FoIP protocol that supports T.30 and converts traditional fax data into an Internet-friendly format.