Hiya, thought this might be useful to others - I run a recording studio-based project for young people 16-25, lots of vocalists/rappers. Lots of them only have a phone and no other tech and so I was struggling find a way to work remotely with them. I found these Tascam DR-22WL recorders which were £110 each with my discount and they are pretty good quality (up to 24/96 stereo) pretty straightforward and have an app which allows files to be sent to a phone wirelessly. From there the app allows you to share files by email/facebook/web.
What I wanted to be able to do was to send them instrumentals to work with and for them to be able to send me back good quality acapella vocal files to mix with. I had one recorder sent to me first so I could get my head around it and they received the recorders yesterday - after some help getting going and recording advice they were already sending me files last night. I have them listening to the instrumental i've sent them on their phone using one earbud, and then they record vox clean into the recorder which they send me to mix with.
Just thought that might be of some help/interest to some.....