This document describes the features of Analog Devices' ADSP-21mod870-110 Internet Gateway Processor Software. The processor supports multiple modulations, including ISDN B-Channel HDLC data modulations and various CCITT and Bell standards modulations. It also supports error correction and data compression features, as well as fax modem modulations. The processor has low power and sleep modes, and is packaged in a high-density 100-lead LQFP package. It also has an on-chip DS0/DS1 interface and a full-function DMA port, without the need for external memory.