Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: internet forums say that we have to buy this from Best nuy only for it to work with comcast
Document: Comcast apparently preloads this modem with software of some sort, and the one I bought via Amazon wouldn't work with my Comcast service. I had to go to a Best Buy with a Comcast kiosk, and buy exactly the same model from them at a much higher price,and that worked just fine. LIve and learn.This is not really a problem with the AMAZON vendor, nor its listing.
It works for Comcast. I was able to activate the internet, but the phone line does not work. Anyway, the technicians came to my place to fix it for free. Buy it to save the $7/month rent fee!
Although the product was listed as compatible with Comcast, and on the Comcast list of approved modems, what was not made clear was that Comcast requires the modem to be acquired directly from them or their kiosk in Best Buy.
Best Buy sells the same unit new for your used cost 69.99. As I found out later. Also one of the LED indicator lights is not lit up on the unit I purchased! does not effect the over all function of the unit. Did cause some confusion  setting it up with Comcast.I need to be more prudent when shopping on line for prices.
These modems are hard to find. I wish I had seen this at Amazon before purchasing it elsewhere because Amazon has the best price. A few weeks ago I searched for the newer TM822G and was hoping to find that but I guess I missed the TM722G if it was available then, which I don't think it was. I ended up purchasing the Xfinity self installation kit from Best Buy for $149.99 and that included the TM722G plus a few misc. cables, backup battery, installation instructions and user guide.
Just got Comcast in October of last year and decided to buy my own modem. This works perfectly in my area and haven't had any issues setting it up or with internet connection at all. Love it.
After purchasing this modem recommended by Comcast, Comcast came to install internet for me and install this modem together. It did not work. The Comcast technician could not get this modem to work after quite a long time trying and ultimately had to remove it and connect a Comcast modem that I have to rent. I really wanted to own my own and not have to rent. Now I am renting Comcast's modem.
I bought this make + model after speaking with a Comcast representative, and checking out the reviews on Amazon. Sure enough it works perfectly with my cable TV, home phone, and internet bundled services from Comcast. The activation part with Comcast took awhile (45 mins.) but it did work eventually.Just installed it 3 days ago, so I will have to check back in, to update on if the quality is maintained over time.
I bought this modem to replace my Comcast leased modem and like many others had issues with the installation but was able to get both internet and phone working. Step 5 was key and I couldn't find it spelled out in any of the forums so I wanted to spread the good word.1. Power down computer, router (if you have one), and old modem.2. Unplug old modem.3. Plug in new modem and power up modem, router, computer.4.
The Comcast representatives were exceptionally friendly and cooperative implementing the changes. Needless to say I am thrilled and an exceptionable positive experience.
Answer: I bought it online and it did not work for my phone. I have Comcasst. It would be better to buy it from Best Buy so you would be able to return if it doesn't work.