Delta Air Lines is to use thousands of Nokia Lumia 820 smartphones to allow its flight attendants to complete on-board transactions easier.

The phones, which run the Windows Phone operating system, will be equipped with Avanade's Mobile Airline Platform, which combines Microsoft Dynamics for Retail software and the Avanade Connected Stores system.

Avanade has integrated the system into Delta's operations and will provide ongoing support, maintenance and system enhancements for the next three years.

The Delta Air Lines deal is a boost for Nokia and the Windows Phone OS in the business space. Overall, only around four percent of smartphones globally currently run Windows Phone and the struggling phone maker has bet its business on the Microsoft OS.

More than 19,000 Delta flight attendants globally will have access to a Nokia Lumia device powered by Windows Phone 8, operating over WiFi and AT&T's 4G LTE network.

The system enables "near real-time" credit card processing for on-board purchases, convenient eReceipts that can be emailed to customers, as well as the ability to read coupons displayed on a customer's mobile device, said Delta.