Serving area interface

The serving area interface or service area interface (SAI) is an outdoor enclosure or metal box that allows access to telecommunications wiring.

Alternate names

  • Access point (AP)
  • Cabinet (cab)
  • B-box (breakout box)
  • Cross box
  • Cross-connect box
  • Jumper wire interface (JWI)
  • Outside plant interface (OPI)
  • Pedestal (ped)
  • Primary cross-connection point (PCP) (UK)[1]
  • Secondary cross-connection point (SCP) (UK)[1]
  • Telecom cabinet


The SAI provides the termination of individual twisted pairs of a telephony local loop for onward connection back to the nearest telephone exchange (US: "central office" (CO)) or remote switch, or first to transmission equipment such as a subscriber loop carrier multiplexer and then to the exchange main distribution frame (MDF).

In the United Kingdom, the components from the PCP onwards to the customer are known as "D-side" (distribution side), and from the PCP back to the MDF as the "E-side" (exchange side). In the United States, the connection back to the MDF is known as the F2 (secondary distribution cable) and/or the F1 (main feeder cable) pairs.

SAIs are used in suburban and low-density urban areas, serving some of the same purposes that manholes do in high-density urban areas. Besides a cross connect point, they sometimes contain a DSLAM or more rarely a remote concentrator or both.

See also


  1. "Multimedia Telecommunications" (BT Telecommunications Series), B. Whyte (Ed.), Springer 1997

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