A UNIVERSAL DSL MODEM WHICH IS CAPABLE OF SUPPORTING BOTH DSL OVER PSTN AND DSL OVER ISDN SERVICE

摘要

This invention is about a Universal DSL Modem that can support both DSL over PSTN and DSL over ISDN services with a single hardware, and the software associated with this ability. The Universal DSL Modem (1) has a DSL Line Interface (11) which can support the DSL-PSTN and DSL-ISDN frequency bands (26, 28). The Universal DSL Modem is connected to the phone line (6) with an End-User High Pass Filter (HPF) (2) whose pass band is appropriate for the DSL service present. Phone Line Terminating Equipment (TE) (4) is connected to the phone line (6) with a Low Pass Filter (LPF) (3) whose pass band supports the phone service present (either PSTN (25) or ISDN (27) ). Software, which runs in the modem, automatically detects the DSL service and executes the appropriate algorithm in the DSP (12) for the DSL variant present. By means of these hardware and software features, the Universal DSL Modem is capable of supporting DSL over PSTN service and DSL over ISDN with the same hardware.