11.1. DSL Unbundling Evolution

Unbundling is the incumbent local exchange carrier's (ILEC's) lease of a telephone line or some part of its bandwidth to a competitive local exchange carrier (CLEC). Unbundling first began in the United States as a consequence of the 1996 Federal Telecommunications Act. Current unbundling practice with DSL service usually allows the CLEC to place modulated signals directly on their leased physical copper-pair phone line, sometimes referred to as the lease of “dark copper.” Such unbundled signals may have services, and consequently spectra, that differ among the various service providers. The difference in spectra can magnify crosstalking incompatibilities caused by electromagnetic leakage between lines existing ...

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