Frame relay has evolved from a solution for piping legacy data across the WAN to transmitting modern LAN protocols, to handling more delay-sensitive protocols, to the current challenge of delivering voice and fax across WANs to branch offices. If you've been searching for an integrated service offering that will let you consolidate data, voice and fax services into one neat package while eliminating the charges normally paid to carriers for traditional voice services between remote offices, frame relay may be just the answer. Now here comes the but that withers the optimism created by all new technology promises. Although frame relay is popular for its flexible bandwidth, its popularity has created traffic jams in the public network. Carriers have had difficulty keeping up with the demands for new service, and many have been slow to develop or even follow technology advancements.
Customers armed with low-cost equipment drive the carriers to new services.
Given nothing more than the demand for higher bandwidth as additional organizations subsc ribe, it is a relatively simple solution for the public carriers to add switches and capacity to the backbone to accommodate the growing demand. The quality of voice transmission is actually determined more by perception than by measurable quantity. The carriers know that voice transmissions can tolerate no more than 350 millisecond to 400 millisecond delays round-trip. Luckily, occasional dropped packets aren't an issue, since the ear can tolerate small glitches without losing the continuity of the transmission, and the retransmission of dropped packets containing voice information often is self-defeating. There are tons of FRADs on the market.