Visit to a BT telephone exchange (CO)

These pictures are of the MDF (Main distribution frame) in a telephone exchange. This is basically where all the wiring from the telephony and data equipment eventually ends up before going out on your line to your home / business. 

These are the modern connectors: 

To give a scale of the size (varies in each exchange):

Old style connectors:

 Top of the frame:

I didn't include pictures of the DSLAM and MSAN's as these belonged to various providers. Essentially they will have cabinets with a HDF at the side.