Editing Digital subscriber line (section)

===Exchange equipment===
[[File:DSL filters at a telephone central office.jpg|thumb|Older stand-alone ADSL filter and splitter banks at a telephone exchange]]
At the exchange, a [[digital subscriber line access multiplexer]] (DSLAM) [[Electrical termination|terminate]]s the DSL circuits and aggregates them, where they are [[handoff|handed off]] to other networking transports such as a  PON network or Ethernet. The DSLAM terminates all connections and recovers the original digital information. In the case of ADSL, the voice component is also separated at this step, either by a filter or splitter integrated in the DSLAM or by specialized filtering equipment installed before it.<ref>{{cite book | url=https://books.google.com/books?id=Jjkd74jY47oC&dq=dsl+filter+rack&pg=PA7 | title=Implementation and Applications of DSL Technology | isbn=9781420013078 | last1=Golden | first1=Philip | last2=Dedieu | first2=Herve | last3=Jacobsen | first3=Krista S. | date=26 October 2007 | publisher=CRC Press }}</ref> Load coils in phone lines, used for extending their range in rural areas, must be removed to allow DSL to operate as they only allow frequencies of up to 4000 Hz to pass through phone cables.<ref>{{cite book | url=https://books.google.com/books?id=mpHoYDO9FH4C&dq=dsl+voice+grade&pg=PA8 | title=ISDN User Newsletter | publisher=Information Gatekeepers }}</ref><ref>{{cite book | url=https://books.google.com/books?id=_zbHY0sLCKUC&dq=dsl+load+coil&pg=PA34 | isbn=978-1-58705-087-9 | title=End-to-end DSL Architectures | date=2003 | publisher=Cisco Press }}</ref><ref>{{cite book | url=https://books.google.com/books?id=3Dn9KlIVM_EC&dq=dsl+load+coil&pg=PA340 | isbn=978-1-58705-119-7 | title=Internetworking Technologies Handbook | date=2004 | publisher=Cisco Press }}</ref>