An AT&T Mobility, T-Mobile USA and Verizon Wireless joint venture, the Isis contactless mobile payments service is set to launch later this year, initially in Salt Lake City, Utah and Austin, Texas.

American Express, along with Visa, MasterCard and Discover, gave its backing to the project last year and has now committed its cards to the wallet, connecting its members and merchant network.

The card firm says that the addition of Serve, its digital payments and commerce platform, to the wallet opens the door to new types of customers.

Josh Silverman, president, US consumer services, American Express, says: "Now our cardmembers and merchants can benefit from the ease and convenience of a tap-and-go experience on a mobile phone and still enjoy the benefits, services and support of American Express."