Demarcation point

The term MPOE (minimum or main point of entry) is synonymous, with the added implication that it occurs as soon as possible upon entering the customer premises.

The ability of customers to buy and maintain their CPE and attach it to the network was stimulated by lawsuits by equipment manufacturers, such as the Hush-a-Phone v. FCC suit.

The newly developed equipment-network separation was codified in Part 68 of the Code of Federal Regulations in the United States and later in comparable regulatory standards in other countries.

The premises-vs.-network separation in the United States, insofar as it affected the former Bell System, was independent of AT&T's divestiture of the local telephone companies on January 1, 1984.

However, CPE interconnection and Bell System divestiture were part of a larger restructuring of the domestic telecommunications industry which took place during the 1980s and are commonly, if inaccurately, seen as one event.

They only contained a spark-gap surge protector, a grounding post and mount point to connect a single telephone line.

Outdoor ones provide easier access, without disturbing other tenants, but call for weatherproofing and punching through a wall for each new addition of wires and service.

Typically indoor DEMARC's will be easily identified by a patch panel of telephone wires on the wall next to a series of boxes with RJ48 jacks for T-1 lines.

This may include in-segment equipment, media converters and patch cords as required to complete the circuit's transmission path to the edge CPE.

The removable panel allows separation of these two parts and independent maintenance, and access to a test socket to determine whether line faults are in the customer's wiring or Openreach's (formerly BT's) external network.

Old and new style demarcation points in a Canadian home built in 1945. A DSL splitter has been plugged into the modern demarc (on the right). One line passes through a DSL filter before going to the old demarc, and from there to the remainder of the house.
20th century Bell Canada demarcation point for a single phone line. The spark-gap surge protectors on the left have hex heads for easy removal. Near center, a post is connected to the house's ground . The other two connection points are for tip and ring . A test jack can be attached nearby so the home-owner or tenant can verify whether the inside wiring is at fault. Modern Bell Canada demarcation points are network interface devices .
Two network interface devices
Demarcation point extension
A British Telecom NTE5 master socket, showing the removable front plate and test socket