original premises POTS wiring and equipment to the new communication channel. Demarcation points on houses built prior to the Bell System divestiture usually do not contain a test jack. They only contained a spark-gap surge protector, a grounding post and mount point to connect a single telephone line. The second wire pair was usually left unconnected and were kept as a spare pair in case the first pair was damaged. DEMARCs that handle both telephony and IT fiber optic internet lines often do not look like the ones pictured above. In many places several customers share one central DEMARC for a commercial or strip mall setting. Usually a DEMARC will be located indoors if it is serving more than a single customer. This may impede access. 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. Each business or individual customer can expect their own separate box for internet access T-1 lines. Demarc extension A demarcation point extension, or demarc extension is the transmission path originating from the interface of the access provider's side of a demarcation point within a premises and ending at the termination point prior to the interface of the edge Customer Premises Equipment (CPE). This may include in-segment equipment, media converters and patch cords as required to complete the circuit's transmission path to the edge CPE. A demarc extension is more correctly termed "Service Interface Extension", and may also be referred to as inside wiring, extended demarc, circuit extension, CPE cabling, riser cabling or DMARC extension. A demarc extension became an important factor to consider in a building's telecommunications infrastructure after the 1984 deregulation of AT&T as well as the supplemental FCC rulings of 1991, 1996 and 1997. Preceding these rulings, the Bell System Companies held a monopoly and did not allow an interconnection with third party equipment. The incumbent local exchange carriers (ILEC) and other local access providers are now mandated by federal law to provide a point where the operational control or ownership changes. This separation between the local access provider and the end user/subscriber is called the demarcation point within a facility (typically a short distance from the