Mobile payments provider, Fortumo, better known for powering in-app payments for Rovio’s Angry Birds “Bad Piggy Bank”, now provides offline in-app payments on Android phones. They have developed a protocol that allows them to use SMS messaging and the billing system of the carrier in order to make the payment when a data connection isn’t available.

Unlike all other major in-app payments solutions for Android (as well as Apple’s App Store) that require the user to have an active data connection while making a purchase, Fortumo’s solution can also be used when there is no data access.

Fortumo pulls this off by relying on carrier billing and falling back to SMS text messaging when there is no data connection. Application sends a text message to a short code. Payment is verified when the application gets back a confirmation text message. Users initiate a payment with a single click, without leaving the application.

Fortumo’s implementation within Angry Birds “Bad Piggy Bank” allows users to dismiss the advertisement without having to leave the application by making a small payment. Now, the same in-game app has been made available to all Android developers for free. Developers can download the library and integrate it into their app.

A smart move on Fortumo’s part, giving away their library for free—and having very few competitors—will give them a strong starting foothold. Especially if they can get other mobile game providers to sign on, especially publishers like Zynga. If people could purchase more coins without having to leave their game while they’re fiddling around with their farm or town they just might buy more purple cows.

The mobile payment company already has billing coverage in 50 companies and about 200 mobile operators. Providing their service without startup fees, monthly fees, and requiring no minimum volume requirements makes it absolutely prefect for small and large developers alike.