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Every telephone company / manufacturer has their own way of doing things: chips, algorithms, techniques and methods for compressing, transmitting, and receiving speech. Not every design that comes out of a company's laboratory rises to the level of IEEE Milestone. NTT 's particular brand of compressing speech is based on a subset of Line Prediction Coding - LPC. Is LSP a real technology or just another math procedure? Is the LSP licensed to other radio manufacturers?
NTT's LSP design was simply accommodated by international standards. NTT did not invent nor create these standards but certainly have encouraged their formation, together with others, and deliberated to ensure their products would be accommodated over mobile channels and the internet. Getting their standards recognized by world bodies was a business or regulatory decision and is not especially noteworthy. Everybody does it.
The phrase ...' contributed to the realization of digital speech communication over mobile channels and the ....". is a bit overstated by suggesting that NTT contributed to my ability to communicate. People in Boston have always found a way to communicate wherever we wanted ever since the days of Alexander G Bell.