Businesses migrating to Voice over IP (VoIP) often find it desirable to move their fax traffic onto the IP network as well. However, VoIP networks are, as the name implies, optimized for voice traffic, and businesses implementing a Fax over IP (FoIP) solution as part of their fax system can benefit from understanding their options for FoIP transport methods. This white paper compares the performance of the two principal options for sending faxes over an IP network: T.38 fax relay and G.711 fax pass-through. It compares the reliability T.38 and G.711 pass-through technologies under various IP network impairments such as latency, packet loss, and jitter.