[asterisk-users] intermittent choppy sound over wifi link

[Andres]

Curt Shaffer wrote:

> I am experiencing a situation where I am getting intermittent choppy 
> audio. Here is the network layout:
>
> Termination provider -> IAX2 over the Internet -> 20Mb fiber 
> connection -> router -> Asterisk
>
> My ATA connection goes into the router between the fiber and the 
> Asterisk server on another interface here is the layout from me to 
> Asterisk:
>
> Sipura ATA (SPA1001 running 3.1.19(SE) firmware), also tested with 
> X-lite softest -> PIX 506 (although I have tried multiple routers and 
> direct connection to the radio try to fix the problem) -> 1 mile 
> 802.11b link to AP -> 15 mile 802.11b link Backhaul -> router -> Asterisk
>
> My Asterisk version is Asterisk 1.2.12.1, Zaptel 1.2.9.1. Ping times 
> are ~10ms, jitter is under 10 with an average of 5. QoS is enabled in 
> the router for SIP, RTP and IAX2 traffic going to and from the 
> Asterisk box.
>
> When I experience the choppiness the ATA reports packet loss on the 
> web interface (Call 1 Packets Lost: ). I can run something such as 
> ping plotter from the same leg of the network that the Asterisk box is 
> on while this is happening and there is not even a small glitch of 
> lost packets on the network but the ATA displays otherwise. The only 
> thing I have come up with thus far is possible retransmissions on the 
> wireless connection (and due to the type of gear, I’m not able to see 
> this data). We are way out in the country with no other real providers 
> even close so I’m doubting interference although I suppose it is a 
> possibility keeping an open mind. My question is can anyone point me 
> to any possible reasons this would be happening? Also can anyone tell 
> me other reasons other than real lost packets that the ATA would show 
> this? My only guess on that was packets that never got an ACK due to 
> server congestion or some other reason other than actual loss.
>
The most likely culprit is jitter.

> Any insight appreciated!
>
> Thanks
>
> Curt
>
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