Web Hosting Talk : Web Hosting Main Forums : Specialty Hosting and Markets : VOIP etc : voip static noise

[jeev]

I've always heard the complaints from my friends office where i've set up a pretty redundant and complex voip network.

I used to have it connected to two servers through dual wan, first call that makes it goes through, due to dynamic and all that stuff, i was getting tired of tweaking scripts...

anyway, now i've got it set up to the point where the dsl/cable here just directly sends the call over icall/flowroute and some smaller providers, the people tell me that sometimes to most times on the other side, they complain about the other side saying there is static...

i'm not too sure when to begin, running jitter tests and stuff, there's nothing to change, im not sure if i should get a license or two of g729 and try it with less bandwidth... the cable here has enough bandwidth to use the internet and call, it does a good two megs.

i'm going to ask them how many calls they have when the static occurs, write down the times.. compare it to graphs and stuff, i dont know what else to check. they are using polycom 330 phones, running freeswitch..

if anyone has any suggestions, please let me know. i'm supposed to set up another one of their offices running 100k minutes but this time i'll send it over a dedicated t1, unfortunately i dont have one to test.

[SysAdminMan]

You could try g729 (you can even get a couple of free test licenses here - www.howlertech.com) but I'd guess that if you've got enough bandwidth for the connection then it might make things worse. If the problem is due to packet loss or jitter then g711 (which I'm guessing you're running) could handle that better.

Have you made sure there is no packet loss on the line? Also, check if you're getting big variations in the ping time. Is there anything else running over the link that could be interfering with the VOIP traffic?

Another things you could try is a different ITSP. It might be a problem with their connections/lines.

[jeev]

well, i've never tried g729, i want to th ough.

it does seem like i have enough bandwidth for the connection, considering at the time of static there are only around 3-5 calls.

i dont think it's packet loss or jitter, i need to start monitoring it on monday with wireshark.

also i have tried many ITSP's, i just wonder if it could be the polycoms

[SysAdminMan]

I've had customers running Polycoms ok, although that is with Asterisk. One thing worth checking is that the handsets are auto negotiating speed/duplex sucsessfully. It might be worth hard coding them and the switch to make sure.

[jeev]

as in, just set them to 100mbit on both sides ? or is there something else that i dont know..

[SysAdminMan]

Yes, that's it. Just set both the phones and the switch ports to 100mb full duplex.

[jeev]

by the way, the static is on and off.

[voipcarrier]

Doing an RTP analysis in Wireshark is one of the fastest and most informative things you can do. When you say static, do you mean white noise like traditional static, or more of a digital jitter noise? Having actual static is not very common, and my first inclination would be to look at the phone itself.

Also, consider if you are seeing this on just one leg, or both legs of the call. Do a packet capture as close to your edge as you can, ideally by doing a port mirror on your switch or router interface. Load the capture into Wireshark and look at the RTP. Assuming that you used G.711 or another supported codec, you can listen to both legs of the audio directly in Wireshark.

[lfc2]

Originally Posted by voipcarrier

Load the capture into Wireshark and look at the RTP. Assuming that you used G.711 or another supported codec, you can listen to both legs of the audio directly in Wireshark.

you can even listen to G729, but not directly from wireshark
you will have to save and process the raw G729 stream