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Executive Summary

T.38 Whitepaper

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. The V.17 and V.34 modem standards are briefly discussed and also used for comparison when used with T.38 and G.711 for performance against IP network impairments, such as latency, packet loss, and jitter. The impact of these network impairments on call control, fax control, and image data are described, as well as the impact of the frequency of these impairments. General considerations for network performance are also covered, as are sections describing how metrics within the Dialogic® Brooktrout® Bfv API can be used to detect IP network impairments.

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