Berkeley Heights, New Jersey-based AT&T Microelectronics has announced the development of a chip set claimed to provide the core functionality for digital telephone answering machines in stand-alone or integrated products. Signal processor-based, the AT&T Telephone Answering Device chip set consists of a ROM-coded AT&T DSP16A1, an AT&T T7513B 8-bit mu-law codec, and an application-specific chip. It is controlled by a system microcontroller via 8- or 4-bit interface using a commandresponse-based architecture, while incoming and outgoing messages are stored in low-cost DRAM using a proprietary memory management system. Indeed AT&T is claiming that with its speech coding algorithm, up to 76 minutes of message storage is available in a 32M-bit addressable memory space. With the addition of read-only memory, a Telephone Answering Device-based product can play synthesised speech and deliver user prompts, instructions, as well as time-of-day stamps, while the chip set also performs dial-tone detection with near-end echo cancellation for remote access to message storage and call progress detection. As an option, the company has also incorporated a full-duplex, acoustic echo-cancelling speakerphone which can be incorporated with the addition of a codec. The company is also claiming very low power consumption as one of the product’s selling points: said to be 85mW, it enables battery powered or backed-up protection against loss of message data. AT&T has made a development kit available which consists of a development board and a demonstration board: the former comprises the chip set, memory and an additional codec, while the latter consists of a ROM-coded microcontroller, key pad, telephone line interface, and interfaces for a speaker, microphone, and handset. While the development kits are available immediately, with chip set samples now, mass production of the set is scheduled for October. The development kit is $2,000 with either board costing $1,000, while the TAD chip set costs $17 in 100,000 quantities.
