33dBm 2Watt GSM900 DCS/LTE1800 Dual Band Phone Signal Repeater Booster Mobile Signals 2G 3G 4G

Telephone repeater
This is used to increase the range of telephone signals in a telephone line. They are most frequently used in trunklines that carry long distance calls. In an analog telephone line consisting of a pair of wires, it consists of an amplifier circuit made of transistors which use power from a DC current source to increase the power of the alternating current audio signal on the line. Since the telephone is a duplex (bidirectional) communication system, the wire pair carries two audio signals, one going in each direction. So telephone repeaters have to be bilateral, amplifying the signal in both directions without causing feedback, which complicates their design considerably. Telephone repeaters were the first type of repeater and were some of the first applications of amplification. The development of telephone repeaters between 1900 and 1915 made long distance phone service possible. However most telecommunications cables are now fiber optic cables which use optical repeaters (below).

Cellular repeater
This is a radio repeater for boosting cell phone reception in a limited area. The device functions like a small cellular base station, with a directional antenna to receive the signal from the nearest cell tower, an amplifier, and a local antenna to rebroadcast the signal to nearby cell phones. It is often used in downtown office buildings.