(Equivalent of 24 Separate Tie Lines) <<<<< NASHVILLE, TN JOPLIN, MO Extension 2415 Rings Dials Extension 2415 in Nashville For calling back and forth between locations without using the switchboard operator. OUTSIDE LINES the T-1 are called dedicated rates. Calls placed on regular PBX trunks are billed at switched rates. T-1 for Local and Long Distance Service Since many telephone companies now provide both local and long distance service, it is possible to install a T-1 that will handle both types of calls. ISDN Lines ISDN is described in the next section since it is also used outside of the PBX. Most PBXs have the capability to accept an ISDN PRI circuit and require a separate circuit board to do SO. The ISDN PRI is a T-1 with enhanced capabilities. Just as differ- ent types of PBX trunks can be delivered via a T-1, they can also be delivered on a PRI circuit. The PRI actually provides greater flexibility, since you do not need to designate each of the chan- nels for either incoming or outgoing calls. Other Types of Telecommunications Circuits (not typically connected to the PBX) Dial Tone Lines This term generally refers to any outside line which, when accessed, a dial tone from the central office switch of the local telephone company is heard. The central office is the point at which all telephone numbers are created. You may also hear the term POTS line (plain old telephone service), or auxiliary, aux line or private line used to describe a dial tone line. It is deliv- ered to your telephone equipment room on two copper wires and may be terminated either on a separate modular jack or on the demarc in the telephone equipment room. PBX combination trunks are also a type of dial tone line, but not usually referred to as such. A dial tone line can be used for receiving calls or placing calls. It has a telephone number associated with it, also called a 224 & The Telecom Handbook Figure 10.8 T-1 to Your Long Distance Carrier LONG DISTANCE CARRIER POP (Point of Presence) (Carries 24 Separate Calls - May Be a Combi