110 block

Early residential telephone systems used simple screw terminals to join cables to sockets in a tree topology.

In commercial settings, this style of home run or star topology wiring was already in use on 66 blocks in telecom closets and switchrooms.

In switch rooms, 110 blocks are often built into the backs of patch panels to terminate cable runs.

[2] Individual Category 5e and better-rated 8P8C jacks (keystone and patch panel) with IDC connectors commonly use the same punchdown 'teeth' dimensions and tools as a full size 110 block.

Repeated use of insulation displacing contacts may lead to a difficult-to-locate broken or intermittently-failing jumper wire.