Registered Jack - History and Authority

History and Authority

For more details on this topic, see Interconnection.

Registered jacks were created by industry and regulated by the FCC to be the standard interface between a telephone company and a customer. The wired communications provider (telephone company) is responsible for delivery of services to a minimum point of entry (MPOE) (physically a utility box) which connects the telephone/network wiring on the customer's property (customer-premises equipment/CPE) to the communication provider's network. The customer is responsible for jacks, wiring, and equipment on their side of the MPOE. The intent is to establish a universal standard for wiring and interfaces, and to separate ownership of in-home (or in-office) telephone wiring away from the wiring owned by the telephone company.

Under the Bell System monopoly (following the Communications Act of 1934), the Bell System owned the phones and did not allow interconnection of separate phones or other terminal equipment. Phones were generally hardwired, or at times used proprietary Bell System connectors.

This began to change with the case Hush-A-Phone v. United States and the FCC's Carterfone decision, which required Bell to allow some interconnection, which culminated in registered jacks.

Registered jacks were introduced by the Bell System under a 1976 FCC order ending the use of protective couplers provided exclusively by the telephone company. The new modular jacks replaced earlier, bulkier connectors. The Bell System issued specifications for the modular connectors and their wiring as Universal Service Order Codes, (USOC), which were the only standards at the time. USOCs are commonly specified to the communications provider by large businesses for a variety of services. Because there are many standardized interface options available to the customer, the customer must specify the type of interface required by RJ/USOC. For a multi-line interface such as the RJ21, the customer must denote which position(s) of the interface are to be used. If there are multiple RJ21 connectors, they are numbered sequentially and the customer must advise the communications provider of which one to use.

When the US telephone industry was opened to more competition in the 1980s, the specifications became US law, ordered by the Federal Communications Commission (FCC) and codified in the Code of Federal Regulations, Title 47 CFR Part 68, Subpart F superseded by T1.TR5-1999.

In January 2001, the FCC delegated responsibility for standardizing connections to the telephone network to a new private industry organization, the Administrative Council for Terminal Attachments (ACTA). The FCC removed Subpart F from the CFR and added Subpart G, which delegates the task to the ACTA. The ACTA generates its recommendations for terminal attachments from the standards published by the engineering committees of the Telecommunications Industry Association (TIA). ACTA and TIA jointly published a standard called TIA/EIA-IS-968 which contained the information that was formerly in the CFR.

The current version of that standard, called TIA-968-A, specifies the modular connectors at length, but not the wiring. Instead, TIA-968-A incorporates a standard called T1.TR5-1999, "Network and Customer Installation Interface Connector Wiring Configuration Catalog", by reference to specify the wiring. With the publication of TIA-968-B, the connector descriptions have been moved to TIA-1096-A. Note that a registered jack name such as RJ11 identifies both the physical connectors and the wiring (pinout) of it (see above).