The device, which can be clipped on to the handhelds, includes a slot for swiping and reading credit cards for payments. It sells for US$655. The MC-75 sells for more than $3,000, depending on the connections it is equipped with. Motorola announced the Snap-on Mobile Payment Device at the conference in New York.

Because the handhelds are able to communicate over both wireless LANs and WANs, it's possible for retailers to swipe credit cards and make nearly instant credit checks in areas outside of normal checkout locations, said Brian Viscount, vice president of marketing for mobile enterprise computing at Motorola, in a telephone interview.

The Snap-on Mobile Payment Device, which attaches to Motorola's MC-70 and MC-75 wireless handhelds, is used to swipe credit cards and make payments.

"Mobility inside of stores is the next wave in customer-facing applications," Viscount said. The snap-on device should be ideal for retailers that don't want to buy a dedicated payment device. About 600,000 MC-70s and MC-75s have shipped globally, meaning there's a large installed base of users for the new device.

Storekeepers can use mobile payment systems for taking payments at sidewalk sales or in aisles away from checkout counters, or even to reduce lines of shoppers waiting to check out, Viscount said. Field workers can also use the devices to take payments.