Comcast and VOIP?

[CaterpillarAssassin]

So we decided to use a hosted IP-PBX system at my office (10 phones), and have been truly disappointed with the call quality. Full of echo's and delay and breaking up.

We were told to purchase an 8Mbit down and 2Mbit up connection to support the required bandwidth. I said OK, and went a step up to the 20Mbit down and 5Mbit up to be safe.

So i've eliminated our office network as the problem (connected phone directly to cable modem (SMC 4 port router modem). Our service provider (for phones) has a "VOIP Speed Test" on their website. I consistently get 2-3Mbits download, and 5-6Mbits upload from there, and similar results to just plain speed tests in the california area (CA, WA, AZ, etc.). Now I've never seen uploads faster than downloads on anything before. Of course I contacted Comcast, and they say everything is fine, signals are good, etc. I would attribute this to just network congestion once it is off the comcast network (i get 30/15mbits to the northeast consistently), but I get 8/3 consistently from home (I live 3 miles away from the office in a different town, with an 8/3mbit connection with comcast).

The only thing different from my home is the cable modem. I have a Motorola at home, and the SMC at the office. Does anyone have any suggestions? This has been going on for 2 months and my employees are getting annoyed! I've had a few techs in and say everything is fine, a higher level tech did some tests on my line a week or 2 ago (for about a week) and said everything was fine. He offered to put in a residential modem to try out (i agreed but it hasnt happened yet).

*EDIT*

By the way, the general problem is the latency. Speed graphs show heavy delay in the download speed, not upload. This is consistent with call quality. Our voice to callers is great, but callers voice to us is terrible.

[FlyingPenguin]

If I understand correctly, you are using a 3rd party VOIP provider, not Comcast's phone service right?

Have you tried doing a trace route to the IP of your VOIP provider? That may show you a bad router between you and them.

I've run into issues with that SMC modem's integrated router and I'm not too impressed with the quality. Many times I've seen strange issues where one of my business clients reports that they can't browse just one certain website (standard page not found error in the browser) and power cycling the modem clears the problem. Apparently the router's address tables get corrupted sometimes due to a memory glitch. You can also try performing a firmware upgrade on it, but the modem's router may just be going bad.

You said you have already tried connecting the VOIP device directly to the modem but have you tried swapping out the modem? Yeah I know it's a pain because you have to authorize the replacement modem with Comcast, but it's the only way to be sure that the problem is not with the modem. I would try a device that's a modem only like the trust Motorola Surfboard and if it works, use a separate router.

Have you considered using Comcast's phone service? Many of my business clients are using it around here and generally they are very happy with the call quality. I have been considering it myself as they have a nice price when it's bundled with your Internet and cable.

I have a doctor's office that uses it with 8 lines. They use their own pre-existing PBX system that they used to use with the regular POTS phone service and have had no issues except for the usual headaches getting the phone numbers transferred.

The advantage is that unlike standard VOIP Comcast is not carrying their phone calls via the internet but instead via it's own back-end outside the Internet, thus (in theory) it's not subject to any latency induced by the Internet (although it can be affected by latency on your node or the back-end) and it doesn't impact your Internet bandwidth.

[CaterpillarAssassin]

We have considered using Comcasts phone service. However, we are now using IP phones that connect to a hosted PBX system. Our old PBX is over 13 years old, and was due for replacement. At this point, we do not want to purchase another premise based PBX.

I had suspected the modem all along, and I'm glad that you can confirm that they are crap. I'm hoping that they can get the modem replaced with the motorola this week.

Results from the trace route below...

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\tom>tracert setup.hostedipbx.com

Tracing route to setup.hostedipbx.com [69.43.168.93]
over a maximum of 30 hops:

1 1 ms 1 ms 1 ms . [192.168.1.1]
2 20 ms 8 ms 9 ms 73.172.172.1
3 16 ms 8 ms 10 ms ge-3-9-ur01.westfield.ma.boston.comcast.net [68.
87.157.129]
4 8 ms 8 ms 8 ms te-9-1-ur02.westfield.ma.boston.comcast.net [68.
87.147.222]
5 9 ms 11 ms 8 ms te-4-4-ar01.springfield.ma.boston.comcast.net [6
8.87.147.241]
6 11 ms 9 ms 13 ms be-11-ar01.chartford.ct.hartford.comcast.net [68
.87.146.26]
7 18 ms 13 ms 15 ms pos-2-5-0-0-cr01.newyork.ny.ibone.comcast.net [6
8.86.90.65]
8 15 ms 23 ms 16 ms ny-twt.host.twtelecom.net [64.132.69.77]
9 112 ms 112 ms 122 ms 207-114-222-94.static.twtelecom.net [207.114.222
.94]
10 110 ms 124 ms 111 ms 207-114-222-94.static.twtelecom.net [207.114.222
.94]
11 113 ms 121 ms 113 ms ge1-2-6509-a.castleaccess.com [69.43.169.112]
12 112 ms 113 ms 111 ms setup.hostedipbx.com [69.43.168.93]

Trace complete.

Looks like pings go up at step 9. Not sure this points to a bad router, though. This is from home, by the way. From the office i usually get a 180-220ms at that jump.

[FlyingPenguin]

Bit of a jump there, but a 113 ping should be okay. You could forward that trace route to your VOIP provider and see what they think.

You should also do a continuous trace route for several minutes. What sometimes happens is you'll see one bad router dropping a lot of packets. The pings may be good most of the time but the packet loss rate is unacceptable.

I use a little utility called UOTrace: http://storefront.steampowered.com/v/gf ... _Trace.htm

My hunch is that it's a problem with the modem's router though.

[CaterpillarAssassin]

tried the util from home. i'll try it from the office tomorrow and see what i get.

Would you mind going to http://www.freedomiq.com/voip-speed-test.shtml and tell me what you get for results? Maybe its simply the provider.

[FlyingPenguin]

[CaterpillarAssassin]

They installed a new cable modem yesterday. It improved download speeds, but the download speed is stil unstable as hell. What gets me is the upload speed is spectacular no matter where I test from. And by spectacular I mean 4-8mbits with delays less than 20ms. Our download speeds have delay spikes up to 300ms and an average of 120ms. Simply aweful. FP, if you go to the graph tab on that test and select "download speed" can you post that graph?

[FlyingPenguin]

Now your VOIP test IS consistently showing my download speed to be around 4.5 Mbit when most any other test I perform shows it from 6 - 8 Mbit. Dunno if that's an issue on their end of the test.

[CaterpillarAssassin]

Mm yeah I am starting to think the same thing. I suppose I should have them look into their connection.

[CaterpillarAssassin]

On the speed tab can you tell me the test #? This will giver some ammunition to go to them with. If anyone else would mind running a test and posting the download speed graph I would greatly appreciate it! Also please give the test number on the speed tab.

Thanks for all of your help.

[FlyingPenguin]

Test# 22427

Here's what I'm talking about. I ran these two tests within seconds of each other. One is your VOIP test and one using Wugnet.com's speed test here: http://www.wugnet.com/myspeed/speedtest.asp

I have found Wugnet to be extremely accurate. They seem to have very consistent servers on fat pipes and they also ignore the "Burst Speed" technology some ISPs (like Comcast) use which gives artificially high download speeds for small files. I have found the Wugnet test numbers to be very accurate, and I can confirm that they are because if I max out my upload and download pipes with Netlimiter running, I can see exactly how much bandwidth I'm using.

Ironically it looks like Wugnet's test is based on the same code as your VOIP test unless they just stole the UI.

As you can see Wugnet is showing 7.62 Mbit for my download pipe. That's normal for me - it hovers between 6 - 8 around here. Comcast only promises 6 but since this is a rural area and there are few other users on my node I generally get more than that.

Your VOIP test consistently says I have around 4Mbit on the download side. The upload side is always dead on.

Now I suspect they will claim that their test is ignoring burst speeds, but I am confident the Wugnet test ignores burst speeds as well. As an example of a test that does not ignore Burst Speed, the third image is from Speedtest.net (who I secretly think is owned by Comcast) showing ridiculously high bandwidth speeds for my connection:

WUGNET.COM:


Freedomiq.com:


SPEEDTEST.NET (obviously being fooled by Comcast's Burst Speed):

[CaterpillarAssassin]

I confirmed that it is our carrier by trying out service from another VOIP provider. Provider still maintains that it is our connection. We will be dumping them soon. Thanks for your efforts, FP