End User Equipment

End user equipment, (often called “terminals”) are the interface between the customer and the network. Terminals may translate electrical or optical signals to forms understandable by people or may be translation devices for other electronic equipment (such as computers).

Most of the telephone equipment in use during the year 2000 converted electrical analog (audio signals) into acoustic energy that the customer can hear. The basic function of analog telephone service is called plain old telephone service (POTS). The standard telephone (also known as a 2500 series phone), continuously monitors the voltage on the telephone line to determine if an incoming ring signal (high voltage tone) is present. When the ring signal is received, the telephone alerts the user through an audio tone (on the ringer). After the customer has picked up the phone, the hook switch is connected. This reduces the line connection resistance (through the hybrid) and this results in a drop in line voltage (typically from 48 VDC to a few volts). This change in voltage is sensed by the telephone switching system and the call is connected. When the customer hangs up the phone, the hook switch is opened increasing the resistance to the line connection. This results in an increase in the line voltage. The increased line voltage is then sensed by the telephone switching system and the call is disconnected.