Some explanations about

Crosstalk in metallic cables,
 the reason for a Spectrum Management

Crosstalk
The used Telecom cables are developped for frequencies up to about 8kHz.
Using these cables for broadband services xDSL (DSL = Digital Suscriber Loop) generates
the problem of crosstalk in cable bundles.

A look inside a cable bundle:

The location of crosstalk:

 

The Power Spectral Density mask of various DSL systems:

ADSL:

 

SDSL:

ADSL and SDSL in the same cable bundle:

The result of the conflict in this case maybe that  the data rate of the downstream of ADSL will be smaller
and/or the data rate of the SDSL system is not as good as proposed.