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The mobile telephone industry has standardized a number of speech coders over the years for use by handheld portable devices. Most of the common ones were developed by the European Telecommunications Standard Institute (ETSI) under the Global System Mobile (GSM) set of standards and then deployed world-wide (with notable exceptions in the United States). These speech coders were greatly limited by the processing power/battery life in early handheld devices and very limited digital channel capacity over the air. Later speech quality/intelligibility improvements resulted from greater signal processing capability in the handheld devices.
When interoperating between networks, most mobile carriers simple convert their encoded voice to the traditional G.711 μ-law and A-law representations even when the non-mobile subscriber is serviced by another carrier or by a Voice over IP (VoIP) service. This results in unnecessary quality degradation which may be considered part of the walled-garden plan. New developments in advanced wide-band speech coders may begin to improve this situation especially if a carrier crosses the boundary between wireless and some sort of wireline replacement service. It is interesting to see VoIP services, such as Skype, carrying speech signals (iLBC encoded) between mobile and all other end-points without the need for additional decoding and re-encoding. Wideband high-definition audio (HD audio) is further discussed here
Using VOCAL's proprietary techniques, extensive code optimization is performed in such a manner that virtually all modern processors (DSP, RISC and CISC) are well supported. Benchmarks have shown that VOCAL's highly optimized C with limited assembly code compares well against other vendors implementations which typically require significantly more assembly language. Typically the difference in performance is within a couple of MIPS. However, the portability and maintainability of our code benefits our customers by lowering the initial costs, easing integration, reduced maintenance costs (fewer coder changes when upgrading compilers), and greater availability of optimized code for different modern processors.