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Switching from old phone modem to new gateway

Regular Visitor

Switching from old phone modem to new gateway

How do I switch my landline phones from our old phone modem (Arris B TM502G) to the newer gateway (Cisco DPC 3941T)?  I have tried many different ways to un-plug/plug-in the phone line and the coaxial cables, but have no luck using the Cisco for phone service.  No dial-tone, no TEL lights.  This unit has been activated long ago for internet and wi-fi.  Any advice?

Diamond Problem Solver

Re: Switching from old phone modem to new gateway

If you don’t see tel lights, the phone side has not been provisioned. Call in and get it activated

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Valued Contributor

Re: Switching from old phone modem to new gateway

Here is a procedure to self activate:



  1. Unplug your old device from the coaxial outlet and plug your new gateway into that same outlet. 
  2. Connect the power connector to the new modem and electrical outlet.
  3. Connect the phone connector (RJ11) to the new modem (TEL1 port).
  4. Wait for the modem to come online. The lights on the modem will let you know when it is online. It may take a few minutes to connect the first time.
  5. Once the modem is online, connect your computer. Do not connect router if any at this point.



Before you start, make sure your account number and telephone number are readily available. This information can be found on your monthly statement or order confirmation e-mail.


  1. Open a web browser. You should automatically be directed to the XFINITY Activation page. If not, please go to
  2. Enter the account information and additional details for which you are asked via the webpage.
  3. After entering the appropriate information, activation will be complete.

If the online activation does not succeed, call customer support: 1-800-COMCAST (1-800-266-2278) or 1-800-XFINITY (1-800-934-6489)


Or Try calling 1-855-652-3446. That is their device activation line.