When it comes to application testing, running your apps on phones is invaluable. To see the features you observed working in the emulator behaving as you expect on a phone is both rewarding and satisfying, not to mention the reassurance it provides that your app is ready to be unleashed on consumers worldwide. However, maintaining a wide portfolio of current phones may be impractical. Aside from the cost, Nokia phones come in a wide variety of regional and operator variants that simply may not be available in your locality. In addition, as new models are release they may not be available in your area immediately.
This is where Remote Device Access (RDA) comes in. RDA is a free of cost service that provides you, as a registered Nokia Developer, with access to a range of Nokia Lumia smartphones over the internet. RDA then enables you to install and run your apps remotely, interacting with the phone as you would if you had it in your hand.
Learn more here.