Earlier this year, when Boingo Wireless Inc. released its dismal 2012 earnings report – one which projected future losses and sent the stock tumbling – there was a tiny flicker of light within. The Wi-Fi provider announced it had worked out a deal for customers of a “top tier U.S. carrier” to use Boingo’s hotspots while abroad.

Today Boingo finally announced the name of that carrier: AT&T. The partnership allows AT&T wireless customers to tap into Boingo’s worldwide network of hotspots in international airports through a special free app. Access will later expand to Boingo’s other hotspots in coffee shops, restaurants, and malls. Using wireless Internet rather than 3G or 4G networks lets users, and AT&T, avoid steep roaming charges.

And the deal goes the other way. Boingo subscribers will now be given access to AT&T’s network of hotspots in the United States. The companies put the combined reach of their network at 1.5 billion people.

What remains unsaid is whether this deal will lead to a partnership domestically where AT&T uses Boingo for “data offloading.” David Hagan, Boingo’s chief executive, has stated that data offloading, where cell customers are seamlessly transferred to Wi-Fi zones to reduce the burden on a 3G or 4G network, is now the company’s future. Especially as revenue from the consumer Wi-Fi business continues to slip.

Hagan called 2013 a “transition year” as Boingo begins to build up that side of the business. But there was no word from executives when or if a data offloading arrangement with AT&T, or another major U.S. carrier, was in the offing.

Boingo’s stock on Tuesday closed up 4 percent to $6.12.