re why is telephone audio hz telephone systems have the capability of a passband of hz to khz the reason they do not implement this is it is not backward compatable to every telephone system in addition the most effecent mix of electrical effecency and intelegability closly mateches a hz khz passband close but no banana to paraphrase garfield the reason hz is used is that voice channels used to occupy khz bands when multiplexed on a trunk line therefore hz at the bottom and hz at the top of this band were filtered to minimise interference with the next band nowadays digital trunks have made this less relevant but the phone companies still see no reason to improve quality especially for free therefore digital chunk of a trunk segments still have a guaranteed bandwidth of only khz so they can carry the equivalent of one analog line at the clock rate of a standard pcm t or e digital trunk it s all historical here in the uk the bandwidth restriction apparently only apply to local lines ie those used by the average domestic client private lines which are run from the local exchange to the leasing client are usually capable of a higher bandwidth if the exchange is digital don t quote me on that but i think i remember a bt engineer saying something to that effect when i was doing some work shadowing a few years ago byeeeee chris name mr chris smith twang on that ole guitar addrs scst uk ac liv csc uni liverpool university quest to build more and more hardware dgree computer science what ever the sun may be it is certainly not a ball of flaming gas d h lawrence all views expressed are my own and reflect that of private thought
