ISDN DSL (IDSL)
provides up to 144Kbps of bandwidth—which is equal to the two B channels
and one D channel of ISDN BRI—by employing the same line coding (2B1Q) as ISDN. It is important
to note that this flavor of DSL does not support analog voice service.
The primary reason for offering IDSL is that the range can be extended to cover virtually any
existing copper path that is devoid of amplifiers or load coils—both of which can be used in very
long analog connections. With repeaters, IDSL can extend to 45,000 feet.