I got an email from Xfinity (Comcast) telling me that my Internet speed had been increased, and that I needed to get a new cable modem. I went to the page they linked to, and found that there were NO DOCIS3.1 telephony modems approved for use by Xfinity. 

I already had an Arris TG862G, but it will not support 250 Mbps download rates. I really did not want to buy another DOCIS 3.0 modem, but I bit the bullet and ordered an Arris Surfboard SVG2482AC from Amazon. It arrived, but try as I might, even with the modem in bridge mode, it blocked access to my dynamic DNS addresses, both from outside and from inside. For example, I have a ejabberd server running on my Linux machine, and I was unable to access it from inside my network at http://mydyndnsaddress.org:5280. Nor was I able to join chats on my own server. So I returned the modem to Amazon, and Googled for a solution.

Many people said to just get a plain internet modem, use it for internet, and use the old one for telephony. So I bought a Motorola DOCIS 3.1 MB8600.

I called the Xfinity special activation number, which answered "Welcome to the Activation hotline," but then gave me no activation choice on the menu! I waited over an hour for an agent. He activated the new modem, and assured that they were both working. For 2 days I got 272 Mbps down and 25 Mbps up speeds.

But this morning, I had no internet. I called 800-comcast, and after the automatic reboot, and a second call, I got to an agent who wanted me to do things like reboot my computer. Finally, she found out that the Motorola modem had been disabled by the Revenue Assurance team. There was nothing she could do about it except to draft an email for her supervisor to send to them, and maybe I would get a call back.

I now know enough to call the Comcast Executive Customer Assistance Team at 215 286-1700. (Ask for the team.) They tried unsuccessfully to activate my modem and said this should not have happened. They referred me to a local (Nashville) executive-level support person, whom they assured me could fix this. But he could not. When Comcast changed their billing system, they made it impossible to use two different modems at once with just one account. He did agree to give me a $10 credit for two years so I could get the higher upload speed (25 Mbps) without paying for it. But I had to use the old 150 Mbps Arris modem. And I doubt that Amazon will take back a second modem. I hope the situation will change in 2 years.

Xfinity has the worst administration system of any company I have interacted with.

  • Comcast did not present me with a viable way of using their enhanced service.
  • There is no way for a customer to know this is not allowed
  • The activation specialist said this was a perfectly normal setup.
  • The Revenue Assurance team should have notified me before killing my service.
  • There is no way for the Executive Customer Support people to change this misguided policy.
  • There is no way for me to contact Brian Roberts (Comcast CEO). All communications are routed to the Executive Support people.


Submitted by Jamie Iverson on Tue, 09/04/2018 - 12:10


well hope they pull there finger out and do something... they can take your money but are not happy giving it back....

Submitted by jarome on Wed, 09/05/2018 - 16:38


Here is my attempt to get support via "Comcast cares" on Twitter:

  1. It is not modem compatibility. It is comcast's refusal to allow separate modems for phone and internet--the ONLY way I can use a DOCIS 3.1 modem and not throw money away.


    https://jamesrome.net/drupal/screwedbycomcast …


    James Rome


    And Brian.Roberts@cable.comcast.com is now disabled, so there is no way to contact him about this sorry affair.

    Sep 4Sent


    Here is a link to a page that lists DOCSIS 3.1 modems can be used for both phone and internet on our service: https://mydeviceinfo.xfinity.com/  -CC


    Sep 4


    I went there and bought one. But there are NO telephony modems listed. Read my blog. You refuse to activate phone on my old arris, and internet on my new motorola.

    Sep 4Sent

  7. You can use this site to determine which wireless gateway will work best for you: https://www.xfinity.com/support/articles/list-of-approved-cable-modems … even tells you how to filter for voice compatible devices. It's not that we refuse, the system doesn't allow it. -CC


    Sep 4


    I do not want to spend money on another DOCIS 3.0 Modem. I bought a recommended omne, and it did not work. You still have not read my blog. You used to be able to do this.

    Sep 4Sent


    There are no xfinity approved DOCIS 3.1 modems. Go to 400 Mbps, and there are 2, but both are docis 3.0.

    7h7 hours agoSent


    We do have approved modems that do both. Please visit the following link, https://www.xfinity.com/support/articles/list-of-approved-cable-modems …, which will give you more information on the devices. -BB

    3h3 hours ago


    Have you visited our website? We do have approved modems. -BB

    3h3 hours ago


    Yes, and if you read my blog, you will see that I tried one and it did not work, so I got a plain Motorola cable modem, and xfinity blocked it (after I had activated it because despite many on your forum saying they do it, you do not allow 2 modems

    3h2 hours agoSent


    What do you mean by we blocked it? BB


    2h2 hours ago


    https://forums.xfinity.com/t5/Your-Home-Network/Xfinity-no-longer-allows-separate-modems-for-voice-and/m-p/3138458#M289558 …

    51m47 minutes agoSent


    We do understand your concerns and apologize for the inconvenience. Do you have another modem you could possibly use? -BB


    39m36 minutes ago

  16.  am using my old one, which will only do 150 Mbps, whereas my service is for 250Mbps. Why can't I use two modems like everyone on your forum that says they do?

    35m32 minutes agoSent


    We can add two modems to your account. -BB


    28m25 minutes ago


    I added two, and the revenue assurance group blocked it!.Read my blog: https://jamesrome.net/drupal/node/177 

    22m18 minutes agoSent


    As stated previously, the (DOCSIS 3.1) modems can be used for both phone and internet on our service: https://mydeviceinfo.xfinity.com/  -BB


    7m3 minutes ago


    No. there are none that you approve. You refuse to listen to me. Go to the page you recommend, fill it in, and there are 2 choices, both DOCIS 3.0. And why won't you read my blog https://jamesrome.net/drupal/node/177  which explains all this?

    Hello, James. Sorry you're unable to use 2 modems one for voice and one for internet. If you are not able to find what you want on the site that is approved. Hopefully soon there will be more Docis 3.1 modems instead of the 3.0 to choose from. You can find out if you are using an Xfinity-approved modem. This link will be helpful to you. https://www.xfinity.com/support/articles/list-of-approved-cable-modems …. -JH

  21. The Technicolor (XB6) Wireless Gateway provides the functionalities of a WiFi router, DOCSIS 3.1 cable modem and eMTA in a single device. If you have both Xfinity Voice and Xfinity Internet service, this Gateway provides an all-in-one way to stay connected and manage your home network. This new Wireless Gateway device supports Xfinity Internet tiers with 400 Mbps and 1 Gbps download speeds with integrated simultaneous dual-band (2.4 and 5 GHz) wireless router capabilities. This equipment is not available to buy 3rd party, but we do have rental options available if you are on the correct speed tier listed above. We do not currently support any 3rd party 3.1 all in one equipment that is available for purchase. -Ryan

    14h14 hours ago


    Finally a proper answer, Ryan. You need to beat upon the previous answerers. But I really hate renting equipment. And I don't understand why I can't use separate modems for telephone and internet. Others claim they can do so. Surely this is an unnecessary burden Xfinity puts on its customers. It should not be halted by your revenue assurance group, since it is legit. And how are customers supposed to know this is not legit? You must go through the forums and add notes saying this is not allowed. If you read my blog, you will see that the Arris 3.0 modem I tried blocked my dynamic dns access (even in bridge mode!), which I need so I can access my system remotely.

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