Comcast has started beta tests of a new cable streaming service called Stream, which will broadcast live TV from HBO and other networks for $15 per month. Launching with Boston, followed by Chicago and Seattle, Stream would let Comcast's Xfinity Internet customers stream live TV over phones, tablets and laptops.

The servic will be available everywhere in the United States by early 2016. It will also offer on-demand movies and recording features, Comcast said.