<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2014) (Learn how and when to remove this template message) </Td> </Tr> <P> A 110 block is a type of punch block used to terminate runs of on - premises wiring in a structured cabling system . The designation 110 is also used to describe a type of insulation displacement contact (IDC) connector used to terminate twisted pair cables, which uses a punch - down tool similar to the older 66 block . </P> <P> Early residential telephone systems used simple screw terminals to join cables to sockets in a tree topology . These screw - terminal blocks have been slowly replaced by 110 blocks and connectors . Modern homes usually have phone service entering the house to a single 110 block, whence it is distributed by on - premises wiring to outlet boxes throughout the home in star topology . At the outlet box, cables are punched down IDC type connectors, which fit in special faceplates . </P> <P> In commercial settings, this style of home run or star topology wiring was already in use on 66 blocks in telecom closets and switchrooms . The 110 block has been slowly replacing the 66 block, especially for data communications usage . </P>

What is the difference between a 66 block and a 110 block