1. A. A local loop is a loop of copper wire that allows a current to flow from a telephone to the central office and back. It is a dual-wire physical interface that connects a telephone to the central office and are typically referred to as a twisted pair. Many of these pairs are twisted together to make a cable for a local loop to provide multiple connections for multiple phone to interface with the local central office.

b. A Central office is a building to which a subscribers home and business lines are connected to a local loop. This office has telecom. Switches to switch calls locally or to a long-distance carrier. A central office is also referred to as a local exchange. The subscribers associated to each central office in their local are identified by the first three digits of their telephone number, however, the last four digits identify the specific subscriber. One central office can support up to 10,000 subscribers with the same three digit prefix. Central offices can also support more than one local exchange.

c. Local exchanges or local exchange carriers are telephone companies that provide service within a designated geographical area or an LATA, local access transport area. One LEC serves multiple central offices depending upon the geographical size and the population of the area.

d. A POP or point of presence in a telephone system is the point where either an LEC or a long distance carrier meets another long distance carrier. A POP provides the interconnection to long-distance carrier or inter-carrier exchange.

e. Long-distance service is provided by an IXC, interexchange carrier, these carriers are used to connect LEC’s together in different LATA’s and sometimes within the same LATA.

f. Bell Telephone Company started installing fixed telephone lines in 1877. Some of the first telephone lines could only