Make sure you get a receipt for the modem when you return it to Comcast!!!
Make sure you keep the receipt. Wait a couple of days and call in and check to make sure they have taken the returned modem off of your account.
Good luck. :-)
You may be able to provision it via their modem registration page (Walled Garden) which you may see by opening up a browser. Follow the screen prompts. Sometimes this fails and you need to call in anyway. If you call, have the make, model number, serial number, and the HFC/RF MAC address of the modem handy. These can typically be found on a label on the bottom.
I bought a Motorola DOCSIS 3.0 SB6121 cable modem which was recommended by Comcast. Unfortunately, it has only 3 hookups (power,cable, and ethernet) and does not have a hookup for telephone. The Comcast rep said that I neeeded the telephone hookup as well. Did I get the wrong modem? If so, what is the correct modem. Thanks.
This is a year old thread. You need an eMTA telephony type modem and a router for additional ethernet ports, or a combo modem / router (not recommended) with telephone support. You have the wrong device if you want to use their digital voice service.
I just installed a new Motorola SB6141 without calling. I swapped the cables to the new modem, cycled power on my router, waited two minutes, and then opened comcast.net. The provisioning was automatic, and even read the hardware info from the modem. I did have to enter my account number, but I still had my account window open in another tab, so I just copied and pasted. For once I had a painless setup on Comcast!