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Old 05-18-2009, 02:10 PM   #1 (permalink)
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Default COMCAST reality with UMA T-Mobile

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Hello -

I realize this is my first post here so let me give you some background.

First, I am a 20+ year career telecommunications engineer with a major tcom provider (wireless and wireline). I moved to the T-Mobile Blackberry Curve SPECIFICALLY because of UMA capability. I want to support an innovator like T-Mobile. While other company's version of innovation is to hire more lawyers and restrict service capability, T-Mobile had the gumption to roll out UMA for $10 as well as a tetherable data plan for $20, so I wanted to support them with my dollars.

I went to T-Mobile 10/15/2008 in the Colorado Springs CO market. My ISP is Comcast. A friend's house where I spend a lot of time also has Comcast as their ISP.

At first, UMA worked very well. I'd say for the first 2.5 months it was good. Then, it went through a period where the quality just went to crap. Echo, drop-outs, just barely usable for communications. This went on from say 1/1 or so to about 5/1. As of about 5/1, UMA would not work at all while my work VPN client was up and running. My VPN client had received a recent software upgrade, so I don't know if was a factor or not, but when the VPN client was up UMA calls could not be made or received. I upgraded the firmware in my Belkin router. This did not help. I switched to a Linksys router. The Linksys does allow my UMA and VPN to work at the same time... until COMCAST kicked in with their new disrupting strategy.

I had 4 days of trouble-free UMA and VPN use. Then, magically, one day BOTH my UMA and my data connection began giving me problems.

The first UMA call of the day would be OK for just over 9 minutes - then it would terminate. At the same time, my outlook email would lose connectivity with the server. My personal computer (non-VPN) would lose internet connectivity. My suspicion is they were blocking connectivity through their "big I" gateway".

After 3-4 minutes, all services would return to normal. My email would see the server, I could browse with my mac, and UMA would come back on. The next UMA call though would start out OK, then have 3-4 second drop-outs of the conversation in both directions. After about 3.5 minutes the call again would terminate and I'd get another 3-4 minute internet brownout of all services.

At my friend's house over the weekend on Comcast I would get poor voice quality as well as a very loud noise spike. As a side note, this friend has the $10 T-Mobile at home service and it works just fine, further evidence supporting the targeting of port 506 of UMA traffic.

It is also worthy to note that when trying to run mac iChat between two macs both on Comcast we experienced similar issues. It works for a while, goes away, cannot connect for 3-4 minutes, connects for a shorter duration, disconnects again... both macs have ichatted at length using non-COMCAST networks for hours before with no issues.


I ordered Qwest DSL, the cheapest/slowest I could get. About $36/month with no contract/commitment. It is about 1.3 meg down/.8 meg up. And of course it works wonderfully with my UMA phone. All the quality and reliability is back. No email, browsing, or UMA issues. I self installed it 5/17 and have had 24 hours of trouble free performance. It was a happy day today when I dropped off the COMCAST cable modem and disconnected my service with them. There is absolutely no doubt in my mind that COMCAST is sabotaging a variety of protocols passing through their network.

I hope this info helps others. It will be posted on other sites.

Last edited by NineHotel : 05-18-2009 at 02:15 PM.
Old 05-18-2009, 02:33 PM   #2 (permalink)
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comcast is the devil
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Old 05-25-2009, 12:11 AM   #3 (permalink)
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Sounds pretty strange to me. I am in NJ and with Comcrap. UMA works absolutely fine in my 8220. I do not think Comcast has any way to track UMA data from zillions of other data. I am nto sure if UMA works thru a particular port liek webservers (80) but if that is not a case, I would be real surprised if Comcrap is atually trying to kill the UMA.
EDIT- you may be able to setup QoS as par this post- blackberryforums .com/wifi-hotzone/ 153789-uma-ports-qos.html
MAKE SURE to remove the extra spaces in the above link.

Last edited by junk2k06 : 05-25-2009 at 12:15 AM.
Old 05-28-2009, 05:03 PM   #4 (permalink)
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The ports used are listed here:

HELP with using UMA on 8320!

They might intermittently block them, but it would mess up other activities, too.
Old 06-18-2009, 03:12 PM   #5 (permalink)
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Thanks for the info - it's very helpful. I am in Denver and have had recent problems as well. I've been thinking about switching to qwest dsl, so I'm glad to hear that it works.
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