US cable company Comcast wants to modify or replace its home customers' wireless routers so that they broadcast two Wi-Fi signals: the private Wi-Fi network accessed by the homeowners, and a separate, public Xfinity-branded Wi-Fi signal accessible to everyone.

This would make every Comcast Internet customer's home a hotspot, potentially knitting together a Wi-Fi signal that could blanket a city. Roughly 100,000 New Jersey Comcast customers are now set up in a test phase.

It is not the only comms company which is trying it. A Spanish company called Fon takes a similar approach with the wireless routers it makes available to its residential customers in the United States and other nations.

The $50 router also broadcasts private and public Wi-Fi signals. The purchase of a Fon router for home use entitles that residential customer to free Internet access via any other Fon router, anywhere in the world.