Arriva is a multi-national transport company operating throughout Europe. The UK division has apps available for both Android and iOS that make it super easy to purchase tickets and travel on the network of buses. Windows Phone still has no official solution, but an app is well in development, according to the Arriva website.
Passengers can use m-tickets on Arriva bus services throughout the UK, except for Park and Ride buses, Fastrack A route and Transport for London services. That said, it's a convenient way to manage your travel without having to carry cash with you. The Android and iOS apps also sport live timetables, maps and journey planners.
We're not sure when this web page was updated, but have reached out to Arriva for more details and will update you accordingly.
Source: Arriva; thanks, Umair, for the tip!