Comcast is playing with the idea of launching a wireless service, and it plans to start network tests next year. On a call with investors this morning, Comcast CEO Brian Roberts confirmed that Comcast has activated an agreement with Verizon that allows it to piggyback on the carrier's wireless network, according to Bloomberg. Comcast has to wait six months before it can use the network, and after that, it plans to "trial and test some things," Roberts said, offering perhaps the most vague confirmation possible. He also told Squawk Box that Comcast could work with Sprint on wireless, too.

The general consensus is that, if Comcast follows through and decides to launch a wireless phone service, it'll likely lean heavily on Wi-Fi connected to Comcast's existing network. Many Comcast routers broadcast an additional signal that can be used by any Comcast subscriber, so a wireless customer could go through most of a day without having to use Verizon's network, so long as they're in a market that's heavily served by Comcast. And given the size of Comcast, that's a lot of markets. Recode reported on Comcast's activation of the Verizon deal last week, and it has more on how the wireless service might work.

Disclosure: Comcast Ventures is an investor in Vox Media, The Verge's parent company.