[Asterisk-Users] Distortion/crackling/skipping problems on outgoing calls -- please help!!!

[Rich Adamson]

> >  
> >
> Thank you very much for your response. I do acknowledge that my previous 
> posts did not contain much technical information to speak of, but it was 
> mainly because I wasn't/am not familiar with the Asterisk CLI and 
> troubleshooting Asterisk problems, so I apologize for that.
> 
> I did get the idea early this morning to try to analyze packets with 
> ethereal, and I captured packets when I was made an internal IAX call to 
> the Asterisk system (voicemail). I don't really know what to look for, 
> but I will learn (again, I'm not very familiar with ethereal). Do you 
> hapeople say ve any suggestions for filters to use, to evaluate possible 
> packet loss or resending of data?

An important item to look at in each packet is the timestamp. In sip
packets, the timestamp should be increasing by 160 for each conseq pkt.
In iax packets, the timestamp should be increasing by 20 for each pkt.

So if you see a timestamp of 3290 in one pkt and 3310 in the next (a diff
of 20), that's good. Notice the increasing timestamp value and the diff.
If pkt 3310 arrives before 3290, then something in the network is delaying
the delivery of packets so as to cause them to not arrive in the proper
order.

If there are missing packets, then you'll see timestamps jumping by 40,
60, 80 or some other value (diff) for iax packets, or, similar for sip
packets.

> Regarding the command that you suggested in the CLI, iax2 show netstats, 
> it doesn't recognize that command or anything similar, and 'help' 
> doesn't return anything similar that I can see (I'm using 1.0.7 if that 
> helps).

Since 1.0.7 is rather old (in the scheme of things), I'd suggest you
install something newer to play with. There has been a ton of stuff
that has changed since 1.0.7, but I don't recall if those changes would
have anything to do with your problem. (I use nothing but cvs head, but
I kind of keep an eye on how many changes are happening (and for what
reason), and upgrade when the number of problems seem to be at a low.
The 'iax2 show netstats' would have been added in a later version.
 
> At this point, I'm thinking that it could be a matter of bad cabling or 
> something. The Cat5 cable that's running the 8 or so feet from my PC to 
> my router is homemade by me, and many people do report problems with 
> homemade cables. I may not have made it exactly right, or the untwisted 
> segment may be longer than 1/2", which supposedly causes distortion and 
> interference. Perhaps I ought to run out and buy a couple factory-made 
> cables to test the difference, if any, between them.

Replacing the cable would probably be a good start since they are
relatively cheap. Go buy a new one so there's no question about its
quality. Also, keep the cable at least a little distance away from
transformers, ballasts, and other things that tend to generate tons
of electical noise. (Some desk lamps even have extremely noisy transformers
or ballasts in them.)