We noted last week that carrier-backed Google Wallet competitor Isis was nearing an official launch when we noticed the T-Mobile ISIS app on Google Play. Today, the app officially launches on all three of its major carrier partners in Salt Lake City, Utah and Austin, Texas. ISIS issued a press release on its website today to confirm the service would be available to nine “Isis Ready” handsets through Verizon, T-Mobile, and AT&T. It will also land on a total of 20 devices by the end of 2012.

“Today’s launch of the Isis Mobile Wallet is a significant achievement in terms of enabling consumer adoption of mobile payments,” said Suzan Kereere, senior vice president and general manager, American Express, Global Network Business.  “Mobile commerce holds the promise of dramatically enhancing consumers’ shopping experience, and American Express’ first priority as a network is to provide choice and flexibility for all industry participants as we work together to influence the speed and growth of mobile NFC payments in the U.S.”

The service will be made available to compatible devices, which the press release failed to list, and it can be activated with a secure element SIM card at one of the partner carrier’s retail stores in Austin and Salt Lake City. We know on T-Mobile you’ll be able to use at least the Galaxy S III and Galaxy Relay 4G. You can see Verizon’s selection here. Isis also has a full list of participating merchants here.

Like T-Mobile, ISIS apps for both Verizon and AT&T are now available on Google Play.

The full press release from Isis is below: expand full story