Coffee chain Starbucks is expanding its Mobile Order & Pay service to 650 locations in the US states of Washington, Idaho, Oregon and Alaska following a trial which has been running in Portland since December 2014. “The ease of use for both customers and baristas is expected to increase speed of service, drive incremental transactions and increase throughput across Starbucks stores,” the company says. The service is planned to roll out across the US during 2015.