Terrible, terrible latency with Verizon DSL

Posts: 9 · New Forum Member Joined: Oct 19, 2009 Posts: 9

Okay, so here is all the pertinent info:
-I'm located in Tampa, FL and currently using Verizon DSL (only ISP we can get around here). This DSL line is ONLY used for VoIP. There are no computers connected to this network unless I'm having to run bandwidth tests or troubleshooting.
-Our usual speed is around 4.5mb/s up and 650 kb/s down.
-The modem model is a Westell 7500 with a built in 4 port router.
-The Vonage devices we use are (I believe) VDV21-VD with 2 phone jacks in the back.
Our set up:
-Westell (4 ports) > Vonage device 1 & Vonage device 2
-Vonage device 2 > Vonage device 3 (daisy chained as suggested by tech support)
Now I know we have quite a bit of VoIP going on here but we only use one line at a time -- total of 4 lines. SOMETIMES there are 2 in use together but this is a rare occurrence.
Our latency issues are very random. Things will get so choppy that we just have to hang up and try again later. It doesn't seem to matter where we call, whether local or across the country.
I've spoken to Vonage tech support a number of times and they have me try a few things:
Change all bandwidth settings on each line to 30kb/s.
Set up port forwarding within the Westell.
Set up Static IPs on each Vonage device.
Daisy chain 2 of the devices together.
Had tech support reset each line (not sure what that is supposed to do).
They've had me run traceroutes and lengthy pings and speed tests that all give desirable results. I was informed if the traceroutes went above 100ms, to contact Verizon. I did this as I saw a few go above 100ms for a slight second. Verizon ran a test on the line and said all our results are good and it must be a Vonage issue. I'm at a loss of what to do since the two companies are just sending me back and forth and I'm getting no where with my service. I don't have all day to spend on the phone trying to fix this either.
Any suggestions would be great!

Posts: 627 · Posted: Mon Oct 19, 2009 9:07 am Post subject:

Does your specific model of the Westell 7500 have wireless capabilities? I am aware that some people do claim this is a wireless gateway DSL modem router and others say it is not.

If yours does have wireless capabilities you need to make sure the wireless function is either disabled or secured with WPA, WPA2, or WEP to prevent unauthorized use. It is possible you are broadcasting a wireless SSID which is not secured like any wireless router by default and someone is leeching off of your connection for free wireless access. This could either be intentional or unintentional.

If this is occurring, someone is utilizing your bandwidth and could cause your "very random choppy audio issue" since isn't any QOS setup on the Westell by default. Not even sure that this Westell could be configured for prioritizing RTP packets.

First thing and quickest would be to identify if your model modem has a wireless router built in and if show disable the wireless or lock it down. You may have to contact Verizon for assistance if you are unable to do this yourself.

Posts: 9 · New Forum Member Joined: Oct 19, 2009 Posts: 9

I disabled the wireless upon setup of the modem.

Posts: 172 · Posted: Mon Oct 19, 2009 2:27 pm Post subject:

Just for the heck of it... can you put a 5 port switch in the middle? Plug the switch into the DSL modem and then remove all the daisy chaining. Each ATA would plug directly into the switch. As long as the modem is broadcasting DHCP it would seem this would be the ideal setup IMO.

Posts: 9 · New Forum Member Joined: Oct 19, 2009 Posts: 9

I don't have a switch to test it out but the original setup had each Vonage device in a separate port on the modem/router. The problems came with this setup as well. I can probably track down a 4 port somewhere and give it a shot if you think it'll make a difference.

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

It sounds like you might have intermittent packet loss or jitter. Unfortunately, it seems that most ISPs will tell you that everything is absolutely fabulous until you prove them wrong... I had a similar experience with Verizon myself. Can you log into the modem and find a diagnostic page that would output such stats as errors and Signal to Noise ratio?

Posts: 9 · New Forum Member Joined: Oct 19, 2009 Posts: 9

I can view quite a few things from inside the modem. Anything specific? For the noise margin, I have 8dB up and 11dB down. I've looked at this before and saw it as 8.9dB down with 11dB up. Don't really know what it means entirely.
There is a lot of info in there so let me know what else would be useful to know.

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

Here are the most important values:

Noise Margin (maybe called Signal to Noise Margin or Signal to Noise Ration or just SNR) - this is how the strength of the DSL signal verses noise in the line -- higher is better.

6dB or below is bad and will experience no synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with no synch problems
20dB-28dB is excellent
29dB or above is outstanding

Line Attenuation - how much signal has degraded between the DSLAM (head end equipment) and your modem -- lower is better.

20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues

Transmit or Receive Power - how much power the DSLAM or modem is using to broadcast to the opposite end -- lower is better.

Maximum recommended value is 15 dB.

---

So, with noise margins of 8dB and 11dB, your DSL line has lots of noise. Its probably right on the edge of losing connectivity completely--hence the periods where the audio breaks up.

Posts: 9 · New Forum Member Joined: Oct 19, 2009 Posts: 9

So I need to bring this to Verizon's attention? Is this something they will come fix?
They keep telling me they're "running a line test" and it comes back perfect. The Vonage rep I spoke to said that usually means they are just running a bandwidth test of some sort.

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

Yes, its something that needs to be brought to Verizon's attention. The SNR is just too low. Give the tech the values your modem reports. They will likely have you do some troubleshooting such as changing the phone cord the modem uses and which jack it is plugged into. If that doesn't resolve the issue, they will need to send a tech out to check the line to identify where the problem is and fix it.