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Started by JeremyW, January 31, 2015, 06:18:15 AM
Quote from: drgeoff on February 12, 2015, 03:40:53 PMSIP will always have an advantage over PSTN/POTS regarding echo and consistency of levels.When you use POTS the analogue audio signals to and from your handset are on a common pair of wires. In your OBi they are separated and amplified or attenuated according to the level settings that you have been tweaking. Then the two signals have to be again on a single pair of wires to travel to/from your telco's switch. There they are separated again for carriage over the digital trunk network.Those separation and joinings are never perfect; there is always some leakage of one direction into the other. Some of the imperfection is caused by the non-ideal characteristics of the 2-wire/4-wire conversion circuits and some is due to the actual line impedance being different from the value assumed in the design of the 2-wire/4-wire converter. Those leakages manifest themselves as echo.In the majority of cases the end result is not troublesome but there may well be some, possibly yours, where there are enough significant shortcomings that their combined effect is troublesome.