New Visitor
Posts: 1
Registered: ‎12-21-2003

installing new modem

After two plus years on Comcast, I have decided to buy my modem and eliminate the monthly rental charge. I am looking at the Motorola SB5100 model. I can do the physical connection ... what else to I need to do to get the modem running? Is there a computer-specific set-up change I must make?
Most Valued Poster
Posts: 8,389
Registered: ‎10-17-2003

Re: installing new modem

I just installed that Modem, it is really nice. Depending on your OS, it should just about install by itself. I have XP and I just plugged it in to the ethernet card. you WILLhave to call tech and get the new one activated and the old one has to be returned to them.
Once you have returned the old one, then when you call, they will need the info on the new one.

Networking Expert
Posts: 24,238
Registered: ‎07-28-2003

Re: installing new modem

No change on your end is needed unless you indend to hook the modem up with USB, which I would recommned against. If you decide to go that route, you will need to load the USB drivers provided by the modem manufacturer. Otherwise it's just hook up the ethernnet cables.

But you must notify Comcast when you install the modem. Depending on your area, the exact method of registration varies, but it all starts with calling Support and telling them you have a new cable modem and asking what you need to do. They may take care of the whole thing, perhaps asking you for the modem's MAC address, or they may have you visit one of the regional SAS websites to complete registration. But it should be simple.
New Visitor
Posts: 1
Registered: ‎01-13-2004

Re: installing new modem

For example (in Los Altos, CA), I contacted Comcast via online chat and was given the following procedure to replace the modem. The procedure varies geographically, I imagine; so start by contacting Comcast. But this gives you an idea what to expect.

Turn off the computer to which the old modem is connected. Disconnect the old cable modem, connect the new one in its place and then turn on the computer. Open Internet Explorer (or whatever browser you use) and enter the address Enter your Comcast account number (from your cable TV bill), and your Registration number (that is the last 9 Digits of the account number). Go through the menu and choose Replace Equipment. Once you are done registering the new modem you should be asked to power down and power up the modem. The next time you turn on the PC the new modem should enable you to connect to the Internet.

The old rented modem can be returned to your local Comcast payment center. To find it, direct your browser to and click on the Payment Center link. They will give you a receipt for the returned equipment, and will also adjust your bill to show that you are no longer renting.