Fix : Vonage on Comcast - audio break up issues/problem

Posts: 5 · New Forum Member Joined: Aug 11, 2005 Posts: 5

cross posted from ZDNET that is wrote:
http://talkback.zdnet.com/5206-10537-0.html?forumID=1&threadID=18445

Fix : Vonage on Comcast - audio break up issues/problem SUGGESTED FIX
gschlact - 03/25/09

March 25, 2009
So there is already so much written about Vonage VOIP issues or audio breakup problems when run on Comcast ISP network.

I think I have the suggested fix / improvement that worked and you can tell Vonage tech support to do on your account. I have spent over 20 hours on the phone with them since December 2008. This worked for both Vonage VDV21 and D-Link VWR adapters.

I concur that despite having very high performance Comcast Service (>12mbps down and >9mbps up, 0% packet loss to yahoo.com, and 42-66ms latency with 45 avg), I was having audio issues with breakup heard by the people on the other end of the phone conversation.

I got lucky one day and the tech said - oh, you have Comcast, you need certain settings... ASK VONAGE TO SET YOUR ADAPTER/ACCOUNT TO USE A DIFFERENT RTP PORT NUMBER (real time protocol) -- set higher in the range. (I then changed devices and this fix was not documented, and took many more hours to figure this out). This resolved and fixed my problem and issue of the vonage audio quality and breakup of outbound audio.

Good luck to all.

-Guy ( gschlact )

PS - if you are having VONAGE DTMF tone problems or issues on voice mail, IVR, conference call systems - TRY Having Vonage Switch DTMF Setting from default/RFC2833 to inband or visa versa. HOWEVER, this didn't totally go away for me until I got rid of the D-Link VWR which simply didn't work reliably on my conference call system no matter what setting. WIth the VDV21, the default RFC setting works perfectly.

Posts: 339 · Vonage Forum Evangelist Joined: Dec 04, 2005 Posts: 339

The only problem with that is that the properties the technical support agent changed only affect the TA and the ports it listens on. In other words, the ports your incoming audio would use. Therefore, no effect on outgoing audio (what the remote party would hear).

While its good that you're no longer having the problem, that was not the solution.

Edit: I should also add that UDP ports are not like pipes that get clogged or congested. While QoS priority (or de-priority) can be applied to traffic using a particular port, if an ISP was to be de-prioritizing traffic (and not saying that they are), they'd be doing it by service type, in this case RTP, not by the port.

Posts: 5 · New Forum Member Joined: Aug 11, 2005 Posts: 5

we'll see if this fixes the problem. it is intermittant.
they implied that the RTP was not just incoming audio.

if it doesn't fix it, i'll report back. Last time (Jan/Feb) with the D-Link adapter, it definitely fixed the audio.

If you don't expect it to fix the outbound broken audio, what settings do you expect might help? Supposedly, Vonage claims there are no known issues when customers have Comcast - unlike many of the forums reports. They definitely want to help, but don't appear to know what else to do.

They have suggested playing with Rx and Tx settings, as well as packet length - do you think they may help?

-Guy

Posts: 627 · Posted: Wed Mar 25, 2009 9:57 pm Post subject:

Quote:

they implied that the RTP was not just incoming audio.

Vonage tech support is only good for instructing customers how to plug in cables between devices. They do not understand the Vonage network or how the service really works. So this type of information taken from them is completely useless. RTP streams between your location and the Vonage media relays. By setting your RTP ports higher on your device, it does not make any difference to a protocol aware application that manipulates packets types based upon priority.

It also has no affect on the port being used at the media relay. Additionally the agents do not take into consideration the NAT factor. Let's say they set your ports to 15050 - 15150 from 10050 - 10150. If you have a Vonage device behind a router, the router may NAT/ PAT the port to something completely different. While the stream between the Vonage device and your router may be 15050, the source port of the RTP leaving your modem could be 42000 or any random port.

Quote:

If you don't expect it to fix the outbound broken audio, what settings do you expect might help? Supposedly, Vonage claims there are no known issues when customers have Comcast - unlike many of the forums reports. They definitely want to help, but don't appear to know what else to do.

If this issue is truly being caused by the Network Management system Comcast is running, there are no settings that Vonage can change on your device or their network. An IP packet is just that. If Comcast looks at the packet and prioritizes it, your going to have issues. Again you state Vonage says there are no known issues with Comcast.

Your speaking to people who answer the phones. They do not know or understand what is going on. This is how it is in any company. The people who answer the phones have no knowledge of what happens behind the scenes. They are just there so callers have a human being to speak to and they collect data from the customer. They are not really the ones actually fix things. The people you spoke to are most likely not even in the US. And it is known within Vonage at the higher levels that there is a possible issue with Comcast but there is nothing anyone can do about it.

And yes, tech agents would like to help, they cannot with these types of issues. So they think they are helping by making random changes to your device. This is known as the "Urban Legends" within a call center. One person makes a random change that they believe is the "Fix All" and it gets passed around. Next thing you know, low level techs are making random changes to customers devices that actually cause more harm then good in the long run. That's why Vonage Engineers have to continuously make changes to lock down more and more device settings the phone techs have access to in order to keep them for making things worse.

Quote:

They have suggested playing with Rx and Tx settings, as well as packet length - do you think they may help?

The answer is no and this is exactly what I am referring to in the previous paragraph. Do you want your phone Volume to be too loud or too soft either heard by you or the party your speaking to? Probably not but that is what the Rx and Tx settings control. It can adjust the analog and digital side of the device to increase or decrease the Volume in or out. This has no effect of the flow of RTP packets to or from your device. As for the packet length, this is how much audio is sent per packet. The default is 20 milliseconds worth of voice per packet. By increasing the packet size to 30 milliseconds, you will lose more audio if you drop a few packets. If you decrease this to 10 milliseconds, you will lose less audio during brief packet loss but it slightly increases your overall bandwidth usage. It also means that you have to be able to send and receive more of these packets to make a complete word so if you have packet loss, your going to end up with hearing bits and pieces of words. And again, this wont help much if your packets are being manipulated by Comcast.

Hope this clears up a few things.