| 摘要 |
A digital subscriber line (DSL) compatible plain old telephone service (POTS) line card that interface a telecommunications switching system to a subscriber over a two-wire subscriber line, wherein the subscriber line card detects whether a DSL line card is connected to the subscriber line. A digital signal processor on the POTS line card is configured to process voice-band signals with a first set of parameters if a DSL line card is connected to the subscriber line and to process voice-band signals with a second set of parameters if the DSL line card is not connected to the subscriber line. Detecting the presence of a DSL line card may be performed by sending a voice band tone on the subscriber line and the return loss measured. Additionally, a tone above voice band may be sent on the subscriber line and a return loss measured. The first set of parameters adjust frequency response of the subscriber line, return loss of the subscriber line and/or trans-hybrid loss of the POTS line card to compensate for the presence or absence of a DSL card connected to the subsource line.
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