Explain Hybrid Network in Standard Telephone hand set.

Hybrid network: The hybrid network (sometimes termed as a duplex coil or hybrid coil) in a telephone set is a particular balanced transformer used to convert a two-wire circuit as the local loop into a four wire circuit as the telephone set and the vice-versa, therefore enabling full duplex operation over a two wire circuit. Fundamentally, the hybrid network separates the transmitted signals by the received signals. Outgoing voice signals are classically in the 1-V to 2-V range, whereas incoming voice signals are normally half that value. The other function of the hybrid network is to permit a small portion of the transmit signal to be returned to the receiver into the form of a sidetone. In adequate sidetone causes the speaker to increase his voice, making the telephone conversation appear unnatural. Excessively sidetone causes the speaker to talk too softly, so reducing the volume which the listener receives.