T-Mobile will roll out its Wi-Fi cellular phone service nationwide in June, reports the Wall Street Journal (via GigaOM). The service allows cellphones to jump onto Wi-Fi networks to help its consumer save money and increase reception.

With a successful run in Seattle under its belt, the "Hotspot at Home" service will launch with a line of dual mode phones using a standard called Unlicensed Mobile Access (UMA).

T-Mobile will also invite consumers to take calls via its network of Wi-Fi "hotspots" available at participating cafes and restaurants, such as Starbucks and Panera Bread.

T-Mobile attempted to roll out a similar service called T One through parent company Deutsche Telekom in Germany. The service was withdrawn for lack of interest.