CM2050V Xfinity Voice Activation

I have a CM2050V on Comcast, and it's fantastic*. I think you're going to be very happy with it.

To activate:

Assuming you have a computer with an Ethernet cable:

1. Turn off your computer
2. Turn off CM2050V (if it's not already off)
3. Attach Comcast coax cable to CM2050V
4. Attach Ethernet cable (minimum cat 5E) between PC and CM2050V
5. Power up PC. If PC is not using the default Comcast DNS server, change settings so it it is.  If you don't know what this means, you're almost certainly using the default DNS server.
6. Power up CM2050V. Wait - the CM2050V may upgrade its firmware and reboot several times. The whole process could take up to 15 minutes. When all lights are lit solidly (except the Multi-Gig light, which should be flashing), proceed to next step.
7. Go to any random web  page.  You should be put into Comcast's walled garden.  Sign in with your  Comcast userid and password. In a few seconds, you should get confirmation that your new modem has been activated.
8. Power down PC.
9. Power down CM2050V.
10. Power down RBR850 (I think that's what you said you had in the other thread).
11. Attach Ethernet cable between CM2050V and RBR850 WAN port
12. Power up CM2050V.  Wait until it's fully booted
13. Power up RBR850.  Multi-Gig light on CM2050V should turn blue to indicate 2.5Gbps connection.
14. Power up your PC.

At this point, you should have working phone and Internet. It can take 24-48 hours for everything to get provisioned properly. For example, Xfinity Stream will probably think you're not on In-home Internet for a day or two. Don't panic, and don't call Comcast unless things really aren't working at all.

*Disclaimer: I was a beta tester for the CM2050V, and received my modem for free. Nevertheless, I think it's a top-notch modem, and I highly recommend it. 

Edit: added step 3 - connect Coax cable to modem.  I know that's obvious, but I just wanted to be complete.