Comcast and Europe's Liberty Global have entered into a partnership that will allow their customers to access each other's Wi-Fi networks. Trials of the shared Wi-Fi service are expected to begin later this year, while a full-scale rollout is planned for 2015. Financial terms of the deal weren't disclosed.

"This is our first step in bringing global Wi-Fi connectivity to our customers", said Tom Nagel, Senior Vice President of Strategic Initiatives for Comcast Cable. The company, which has more than three million Xfinity WiFi hotspots in the US, expects to have eight million Wi-Fi hotspots by January.

On the other hand, Liberty Global, which is based in London and largely controlled by media mogul John Malone, has about 2.5 million WiFi hotspots under the Wi-Free and WifiSpots names in various European countries including Belgium, the Netherlands, Ireland, Poland and Switzerland, and the number is expected to grow to more than three million.

"We are delighted to join forces with Comcast to begin building worldwide Wi-Fi connectivity and we hope that this will create interest from other cable operators to join us", said Balan Nair, Executive Vice President and Chief Technology Officer at Liberty Global.

The companies said the agreement will provide many of the 11 million Americans visiting Europe and the 12 million Europeans visiting the United States each year a free alternative to cellular data roaming. 

The news comes just a few days after it came to light that Comcast is inserting ads on websites you visit while using the company's publicly accessible Wi-Fi hotspots in the US. Meanwhile, the cable company's $45 billion purchase of Time Warner Cable is also facing regulatory scrutiny from the FCC, and stiff opposition from some big media companies.