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The use of asynchronous adaptive sampling for multiplexing multichannel analog signals and data over a synchronous digital facility is examined. This method promises to provide an efficient and consistent way to digitally transmit voice, line-scanned graphics or text, and data. Buffer analysis, computer simulations, and laboratory prototypes are described. When multiplexing speech using extremal sampling, quality of about 32 000-bit companded pulse-code modulation (PCM) is achieved at an average bit rate of 13 000 bit/s per user. Idle spaces, up to 20 percent of the link capacity, can also be filled with indirect data. The potential demonstrated in the laboratory indicates that effort should be directed toward reducing system complexities so as to achieve an efficient, practical system.