Time Division and Frequency Division multiplexing systems have traditionally provided the bulk of voice communications throughout the world. The technical issue of variable end-to-end delays have slowed the integration of voice communications into frame and packet-based data systems.
However, new advancements in DSP (Digital Signal Processor) technologies have resulted in variants of Low Bit Rate Voice algorithms that can withstand (to an acceptable degree) the variable end-to-end delivery rates presented by frame and packet data systems. Thus, there are a couple of new transport mediums available for voice circuits. The first is the Internet, which is packet-based. This will likely become a medium used for public transport of voice data. The second is Frame Relay, a frame-based switching system that is likely to gain large acceptance for private networks.
Both systems have merits and drawbacks. The Frame Relay approach assumes that one does not have a high discard rate. These discards can occur with noisy or overloaded links. So there is risk using this with Internet providers, as many ISPs that use Frame Relay have little or no regard for discard rates. But in private networks, or a good Public Frame Relay Carrier, this is an entity that can be controlled through proper configuration planning and traffic load analysis. The Internet Protocol (IP) approach is a little more difficult from an algorithm perspective, since there may be larger variances in end-to-end delivery of digitized voice information.
The following is a list o' links that provide some sources of technical information on these techniques:
Internet Systems (IP)
Frame Relay Systems
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