I had a Comcast cable modem go out on me the other day - dead, finis, kaput. So I took it to the Comcast office. While I was there, I thought about my Fios modem, which has a wireless router built in. Maybe Comcast has a similar thing, so I asked.
I was told they did not have such a thing, but if you rented a modem from them (which most people do), you could get a router free for the asking. Of course if you cancel your service you have to return it just like the moxdem. So I asked and I got one, along with a new modem, and hooked it up and voila, wireless.
I can't remember if the installer told me about this deal when he hooked up the Internet connection.