[ntp:questions] Accuracy of audio tones via VOIP

David Woolley david at ex.djwhome.demon.invalid
Wed Jul 10 08:48:09 UTC 2013


On 10/07/13 00:07, Harlan Stenn wrote:
> John Hasler writes:
>> Landline long-distance usually goes over packet-switched networks as
>> well these days.  Unless your call to NIST is local you probably
>> aren't hearing the tones they sent.
>
> I have heard (and I haven't checked in to this) that a good number of
> local calls are converted to digital pretty quickly, too.  It would be
> interesting to find out and do a study from a variety of locations.
>


That's been the case for over 25 years in the Western world.

Note that neither digital networks, nor packet switched systems (whether 
the older ATM or more recent IP ones) forces the use of speech codecs - 
phone systems do still have to handle modems.  As far as I know, all BT 
calls within the UK are provided over a 3.1kHz audio bearer service.

All business PABXes are digital these days.



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