Is Telephone Line(Land Line) communicate through RS-485 Protocol ?
First a general answer. The standard that you mention is for RS485 or EIA (Electronic Industries Association) RS485 is a balanced line, half-duplex transmission system allowing transmission distances of up to 1.2 km. So it is for data transmission only, and can be used to daisy chain a number of devices on the same line, or in a point to point application. The half-duplex means that only one device can talk at a time. This is definitely not for a voice application and I am not sure why this would be used very much standards as frequency shift keying (FSK) and Quadrature Amplitude Modification can get high data rates (for telephone lines) and are full duplex. If there was limited cable facilities and the devices could operate at lower data rates, then using this in a daisy chain application would make sense.
