ExpressPay, which the company began piloting last summer with its employees in Phoenix, is now available at more than 175 merchant locations in the greater Phoenix area, including all Carl's Jr. locations, and participating Dairy Queen, Kwik Kopy Printing, Quiznos Subs and Schlotzsky's Delis.

Users simply hold the ExpressPay key fob next to a companion reader at checkout to make purchases. Payment is authorised in seconds and no signature is required. ExpressPay links directly to an existing credit, charge or debit card to fund the purchase.

Consumers have the option of funding ExpressPay either as a direct link for payment to an American Express Card or as a pre-paid product linked to any major credit, charge or debit card.

David Bonalle, vice president and general manager of advanced payments, American Express, comments: "We have found in testing that consumers prefer using their ExpressPay key fob rather than fumbling for their wallets, while merchants enjoy the benefits of their customers' increased spending and reduced time at the checkout counter."

Results show that participating merchants have seen customer spending increase by 20%-30% compared to their cash spending, while customers have seen their checkout time reduced by 30%-40%.

The Phoenix rollout expands on the pilot the company began a year ago, when it introduced the contactless key fob to several hundred employees for use at its corporate cafeteria in Phoenix, and at a handful of area merchants. In the autumn, ExpressPay was market tested with non-American Express employees in New Jersey, and earlier this year at a cafeteria serving a major financial institution and at American Express' headquarters cafeteria and convenience store — all in downtown New York.

ExpressPay uses RFID chip technology from Texas Instruments and is compatible with the ISO/IEC Standard 14443 endorsed by Visa and MasterCard.