By announcing Atlanta, Nashville, Chicago, Detroit and Miami as its initial rollout destinations for DOCSIS 3.1-powered gigabit-speed broadband services, Comcast (NASDAQ: CMCSA) seems to be very clearly calling out AT&T.

In fact, the MSO is targeting all markets where AT&T is also offering its GigaPower 1 Gbps service. AT&T itself, the very next day after Comcast's announcement, said that it would expand GigaPower in four large metros.

But what's even more compelling from a capital investment point of view is that Comcast can deliver those gigabit speeds over its existing hybrid fiber-coax (HFC) plant. Unlike FTTH, the operator does not have to build out fiber and install facilities at each house or business to deliver service.

Comcast said it will equip customers with the services by having them plug in a new modem with gigabit capabilities once the speed tier is available in a particular area. FierceTelecom Editor Sean Buckley examines the emerging showdown in his latest column. You can read his full Editor's Corner here.