[rescue] 802.11 + VoIP

Joshua Snyder josh at imagestream.com
Thu Oct 16 23:47:59 CDT 2003

On Fri, 17 Oct 2003, Geoffrey S. Mendelson wrote:
> Performance is not an issue with VoIP, latency is. To get a decent VoIP
> connection you need to sustain 64k BITS per second of DATA, which means
> about 96k-128k of IP throughput. Just about any WiFi network can do that,
> but if the delay is too long in getting a packet out there, then there
> will be echo and other problems.

The other thing to remember is that wireless will have variable levels of
quality.  From my experience latency can be a problem when doing VoIP over
wireless but packet loss will kill you.  VoIP almost always uses UDP
packets and UDP packets do not have guaranteed delivery.  So if you have a
bad WiFi signal and you have a large amount of packet loss the phone will
just cut-out on you... Just ask Dan Sikorski, just two nights ago I called
him via a VoIP phone.  In this case the last hop before the phone switch
was over a woreless connection at the time the signal was very bad and
even though the latency was only about 150ms the packet loss was around
12%... it didn't take long for us to switch back to using Icq.  Other
times I have use the exact same setup and have had no problems... your
mileage may vary.


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