[rescue] VOIP

Patrick Giagnocavo +1.717.201.3366 patrick at zill.net
Sun Oct 12 23:21:24 CDT 2003

On Sun, Oct 12, 2003 at 07:51:56PM -0400, Al Potter wrote:
> patrick at zill.net said:
> >  The neatest thing I saw was a Compaq iPaq with Wifi and the soft
> > phone they have; you could dial out and use it like a normal cell
> > phone.
> Except 802.11 was never intended for this kind of use, and voice quality is 
> GOING to suck, particularly when you roam.

Well, I don't think that it would particularly be a problem in most
cases.  With overhead, etc. the most you can get on 11mbps 802.11 is
about 3mbps full-duplex .  But you might only need 128kbps or less for
good voice quality.  Vonage does it with less than 90kbps; as long as
your latency is not too bad (say under 95ms ping times) you would be OK.

There are so many different ways to set up an extended Wifi network
that quality of roaming experience would really depend on the design
of the network.  Generalizations on this matter would generally be

> The other lovely part is that with no 802.11 link encryption, or with WEP 
> which is almost the same as none, your calls are trivially tap-able.  If you 
> haven't already, take a look at vomit, written by a friend of mine:

I live near the Amish. "VEP" is not something they worry about.

Seriously though, yes, you would want IPSec; on the iPaq, there would
probably be enough CPU to do that and not suffer degradation.

This did not stop the demo I saw from being neat however.

Just curious, do you use a cordless phone at home or office ?


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