Is the process of sending and receiving faxes via a VoIP network. 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.