Advances in coding algorithms and digital signal processing have led to sophisticated technologies for speech communication for a variety of applications, as well as to greater flexibilities in the design of ISDN terminals for integrated communication of speech, images, and data. For traditional telephony with a signal band‐width of 3.2 kHz, the transmission rate for network‐quality speech is now down to 16 kb/s. Robust communications‐quality speech appropriate for cellular radio has been realized at 8 kb/s. Research attention is shifting toward 4 kb/s, focused on improving speaker identification and the naturalness of coded speech. For wideband audio with a signal bandwidth of 7 kHz, high‐quality coding is now possible at 32 kb/s, which implies stereo teleconferencing or dual‐language programming over a 64‐kb/s channel. Transparent coding of 20‐kHz audio has been demonstrated at 128 kb/s, with near‐transparent performance at rates as low as 64 kb/s for some classes of signals.

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Inthis paper, we discuss speech processing applications inthe integrated access and cross-eonnect system, digital cellular telephone system, operator services position system, and intelligent networks. These applications are used to show how the AT&T Network Systems product line allows telephone companies and business customers to implement solutions based onend-user characteristics, expectations, and requirements.

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