Activate Other Coaxial Outlets in Home

xfinity will only install to a single drop.  For what you want to do, you will have to find a contractor familiar with setting up whole house Coax.  It is not as simple as running coax to all the outlets.  If you were to attempt this, you would not have any usable signal in any room because of the number of times it would need to be split.  The signals will have to be amplified and balanced. It will not be cheap, either.  Good luck. 

@user_a88083 

Did they ever work ? You could try tracing the lines back to a centrally located splitter (if it actually exists) and see if they are connected. Perhaps it may be in the basement, attic, garage, crawl space, or a closet somewhere. 

An Xfinity tech can investigate / help you out, install lines, a splitter, or an amp if need be.

... you would not have any usable signal in any room because of the number of times it would need to be split. ...

Which is why Comcast installs 5 or 9 port zero-gain splitter/amplifiers when connections to multiple devices are needed. These are available at retail from Commscope or PPC. The units combine a splitter with an amplifier so that, upstream and downstream, amplifier gain = splitter loss. Examples are https://www.amazon.com/Active-Return-5-Port-Amplifier-PPC-5M-U/dp/B086R3HCF2 and https://www.amazon.com/CommScope-CSMF1APDU9VPI-HomeConnect-Amplifier-Spectrum/dp/B07TN963JJ.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Thanks, @BruceW. I generally do not recommend amplified splitters, because they also amplify the noise; at least the affordable ones do.  Back in the day, in the military, when we were cabling large installations with hundreds of clients, we of course used optical, along with a host of ODS boxes, junctions, repeaters and attenuators.  On smaller projects, we would run coax and sometimes used the type of splitter you mentioned. We used one of two types; one, manufactured to military specs, performed very well but were terribly expensive.  If we used the commercially available ones, we never had an install where there were not signal issues.  Granted I have been out of that for quite a while, but I cannot imagine that it is much better today than it was then (hence the move to fiber in the civilian sector).  Do you use such a splitter/amp in your home?  If so, are you happy with it's performance?

... Do you use such a splitter/amp in your home? ...

I do not. I use a passive 2 way splitter to feed a TV set and a cable modem. So no, I have no personal experience with the zero-gain devices . My post was of the "this is what Comcast does" type. As we know, sometimes "what Comcast does" is pretty good, and sometimes not so much.  😉