Quality Problem - Delay Issues

Posts: 3 · New Forum Member Joined: Nov 02, 2008 Posts: 3

I've had Vonage for several months now, and love everything about it expect for the quailty of calls. Specifically, I've been experiencing a slight "delay" when talking with others, whether they are on a cell phone or a land line. One person will be talking, and I'll say something while they're talking, but they won't hear it until a few seconds later and so will keep talking and eventually we both fall silent and have to take turns talking instead of having a fluid conversation. I was hoping this problem would be temporary or intermittent, but it has been happening on every call the whole time I've had service. I've talked with others who have Vonage and they do not have the same problem, so I'm hoping there is some way to fix it.

My info:
1. Location - Winter Haven, Florida
2. Your ISP name - Roadrunner cable
3. Upload - 7Mbps, download - 500Kbps
4. Modem - Toshiba PCX2500
5. Vonage adapter - VDV21-VD
6. Setup of Network - Modem-->Router-->Vonage Adapter
7. Issue you are experiencing - Delay
8. Run this Voip Test:

Speed test statistics
---------------------
Download speed: 6747664 bps
Upload speed: 492368 bps
Quality of service: 97 %
Download test type: socket
Upload test type: socket
Maximum download pause: 14 ms
Average download pause: 1 ms
Minimum round trip time to server: 41 ms
Average round trip time to server: 42 ms

Voip test statistics
--------------------
Jitter: you --> server: 1.0 ms
Jitter: server --> you: 3.5 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Number of supported Voip lines: 8
Estimated MOS score: 4.0

Thanks in advance for any help you can give!

Posts: 656 · Posted: Sun Nov 02, 2008 6:32 pm Post subject:

In all the time you had Vonage, I bet you requested to swap out devices or it was suggested by Tech Support. But, have you ever changed out that modem of yours?

I am almost 100% sure it operates at 10Base-T half duplex.

After just finding the manual and looking at the specs, I am completely sure it is operating at half duplex. While half duplex is OK for TCP based internet traffic, it will not suffice for UDP protocol RTP(Real-Time Transport Protocol) packets which is what your audio stream is or any other bi-directional media for that matter.

Here is a good definition so you better understand the terminology of half duplex.

half-duplex - Refers to the transmission of data in just one direction at a time. For example, a walkie-talkie is a half-duplex device because only one party can talk at a time. In contrast, a telephone is a full-duplex device because both parties can talk simultaneously. Duplex modes often are used in reference to network data transmissions

You may also have an older hardware and software version modem which is only operation at DOCSIS 1.1 and needs to be at least 2.0 for optimum quality and bandwidth. It doesn't hurt to get an upgraded modem from your ISP which should also be able to increase your overall throughput. Just make sure the modem is a standalone bridged modem. This means a modem without a built in router or voice adapter.

Go to the end of the PCX2500 modem manual and look at the specs of the PC Interface. A good modem would need to be 10/100 half/full/auto sensing.

http://www.toshiba.com/taisnpd/products/pcx2500manual.pdf

Posts: 3 · New Forum Member Joined: Nov 02, 2008 Posts: 3

Excellent information, I had no idea that my modem was half duplex! The problem makes more sense now. Smile

I'll get my modem swapped out with a newer full duplex model and hopefully that will solve it!

Thanks so much for your quick and thorough response.