FoIP gateways-architectures, implementation and QoS issues

摘要

Real-time facsimile communication over the Internet is a challenging task. Facsimile devices and protocols have been optimised for facsimile communication over PSTN (public switched telephone network) links. To allow these devices to communicate over the Internet, FoIP (Facsimile over Internet Protocol) gateways are required. Source and destination facsimile machines connect to these gateways over PSTN links. Peer gateways are connected to each other over the Internet. The inherent best-effort nature of the Internet poses serious QoS (quality of service) issues for facsimile transmission. Packet losses, delays and delay variations may disrupt a facsimile session. FoIP gateways providing real-time FoIP communication need to incorporate measures that attempt to provide efficient and reliable transport service over the Internet. This paper describes typical architectural components of FoIP gateways. QoS issues related to real-time FoIP transfer are highlighted and measures are discussed that assist in resolving these issues.