Archived from groups: comp.dcom.voice-over-ip (
More info?)
Rusty Shackleford <DieSpammerDie@njabl.org> wrote in message news:<MPG.1c82c157e12b32db989700@news.comcast.giganews.com>...
> In article <eaa2ab80.0502190204.51c715b1@posting.google.com>,
> google@bathfordhill.co.uk says...
>
> > For G711 each sampled packet is 64K + approx 12K of overhead and this
> > is each way.. SO a conversation using full duplex will require approx
> > 80K in each direction G729 is 8K + 12k therefore 20K in each
> > direction. If your router supports stats you will see this.
> >
> > Ian
> >
>
> A router WOULD see such numbers, as it is handling TWO connections, one
> upstream and one downstream. An END POINT (soft phone, IP Phone, etc.)
> requires approximately 88 kbps for a G.711 conversation, not 196 kbps.
>
> You can read here, for a more thorough explanation:
>
http://www.voip-calculator.com/bandwidth.html
And in the real world a call is made up of two parts:- Upstream and
downstream. and for example my sftphone is full duplex and I CAN see
the conversation and the bandwidth is 79K in EACH direction. The site
you mention is only taling about transmiting packets. Try it for your
self. Setup calls on an ADSL line and your callers will get serious
degridation after thr 3 or 4th call ( based on 256K upstream link
wereas you wont hear any degridation.
This experiance is based on Lab testing and Packet sniffing with
Mitel, Cisco and Asterisk IP PBXs
When designing IP networks the bandwith consideration has to be based
on FULL duplex IE 80K or 20K in each direction. The fact that yes
people often dont talk when someoe is taking to them doesn mean they
wont. Or for even more of a laugh and to see the effects of your
theory set the switch port to half duplex then try having a
converation.
Ian