[152567] in North American Network Operators' Group
VoIP/Mobile Codecs (was Re: Operation Ghost Click)
daemon@ATHENA.MIT.EDU (Sean Harlow)
Wed May 2 17:40:40 2012
From: Sean Harlow <sean@seanharlow.info>
In-Reply-To: <4FA194B4.2070706@mompl.net>
Date: Wed, 2 May 2012 17:40:02 -0400
To: Jeroen van Aart <jeroen@mompl.net>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On May 2, 2012, at 16:10, Jeroen van Aart wrote:
> Technical specs aside I believe you are mistaken with regards to the =
actual every day reality. My experience (and anyone else I talked to) =
calling to and from mobile phones has been 100% a bad one with regards =
to audio quality. I know the bandwidth allows for better quality, but =
carriers don't do it, they do the opposite.
>=20
> Why else would a mobile phone carrier feel the need to advertise an =
"HD" (shouldn't it be "HIFI"?) quality line (i.e. a quality that's =
standard with every land line and already suboptimal):
>=20
> http://www.pcmag.com/article2/0,2817,2402598,00.asp
>=20
> "Sprint Brings HD Voice Calls to U.S."
Originally, you said VoIP and cellular used bad codecs. I responded =
that any decent VoIP provider supports codecs equaling or beating =
landlines. I didn't say anything about cellular. A G.711 call over a =
solid internet connection will sound entirely identical to any landline =
telephone call that leaves the local analog facilities and a G.722 call =
will make G.711 and thus landlines sound like cellular by comparison.
The cellular world works with less bandwidth and more loss than the VoIP =
world usually deals with, so while us VoIP guys sometimes use their =
codecs (GSM for example) they don't tend to bother with ours. That =
said, the article you link is talking about the same sort of =
improvements by doubling the sampling rate, so the end result is =
similar.
---
Sean Harlow
sean@seanharlow.info
