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[Future9] Jitter problems

Well, I haven't noticed any unusual audio glitching on my calls lately. Jitter is right up my alley, so I started testing. I sent off a test fax @ 14400, which reported a low number of Ecm retransmits. Trying different areas to try to catch different carriers I did try dialing into several Isp modem pools. There wasn't an issue syncing up even at v.92, v.90 or v.34. It's a good test since if even high speed modems can even sync up, your ears aren't going to notice. It's possible it's still with the did carrier, or some other outbound carrier I missed, but also even with high bandwidth available, things can still be jittery. You can test your connection with some online Voip test which test for jitter. Search for "voip test" and there are several reliable ones, just don't test with one and take that as a final result.

reply to baj475
Jitter, also called Packet Delay Variation (PDV), would more likely be an issue with your Internet Service Provider (Comcast), rather than an issue with your carrier (F9). And download/upload speeds have little to do with it. Many Cable TV ISPs have problems with jitter as a result of shared connections with your neighbors, and the resulting congestion on your cable modem's Internet frequencies.

Here are a couple of tests you can run to check Jitter levels:

»myspeed.visualware.com/indexvoip.php (Acceptable jitter levels on this test should be under 5ms)

»pingtest.net/ (Acceptable jitter levels on this test should be under 10ms)

Hope this helps.

Just a note on these jitter tests such as pingtest.

You want to use a server that is closest to the gateway of your VoIP provider.

Testing jitter to a nearby test site may give a good result, but if your gateway server is across the country, then use that for more accurate results.

reply to baj475
Are you using the incoming, or outgoing server?

Try to set your jitter buffer to something like extremely high and not adjustable and see if that helps. It might introduce some delay, but help jitter - see which way works better.

reply to jason_m
I would be interested in knowing what test there is out there that would reports the number of ECM re-transmits.

I would think that only the receiving fax machine would have that data. Possibly the sending fax machine since it would theoretically receive all of the EMC re-transmit packets.

However, since EMC re-transmit is not a function of the IP protocol, I am unaware of any such tests that exist.

The whole concept of faxing over VoIP honestly confuses me. Just scan the document and send the file via email.

Right, because the media likely stayed on your internal network.

I would expect faxes to work flawlessly in that example.

reply to baj475
I'm still puzzled how F9 or any other VOSP can impact jitter. Packet delay variability is very unlikely to come from the VOSP's hardware or connection. IIRC it's almost always a server withing the route having traffic or other variations that cause that.

reply to baj475

reply to baj475