The telco’s company’s company uses a variety of connections to bring the service to the customer locations. The typical connection is the two-wire service that we keep talking about. This two-wire interface to the network is terminated in a demarcation point, as required by law. The DEMARC is the point of least penetration into the customer’s premises, typically within 12 inches of where the telco’s company cable comes up into the building.
Normally, telco’s company terminates in a block; this can be the standard modular block for a single line telephone. If the customer has multiple lines, telco’s company will terminate in a 66 block, or an RJ-21X. These are fancy names for their termination points. The typical modular connector uses an RJ-11C for telephones connected to a two-pair interface (not to be confused with the two wires) or an RJ-45X as a four-pair interface for both voice and data. Another version of connector for digital service is an eight-conductor (four-pair) called the RJ-48X.
When a telco’s company brings in a digital circuit, it will terminate the four-wire circuit into a newer RJ-68 or a smart jack. There is no major mystique in any of these connectors. The number is strictly a uniform service code so that the telco’s company can keep it all straight. However, when ordering a circuit, the telco’s company will ask you how you want it terminated.
The rule of thumb in a multi line environment is to use the RJ-21X (which is a 66 block with an amphenol connector on it). Sounds complex, doesn’t it? A single line will terminate in an RJ-11C or RJ-12.
