It is quite a simple app premise - the user logs in and downloads one central csv file everytime telling them what work they have to complete.
If the allocated work falls within the date and time restriciton on the devices current date and time, the work can be started and undertaken.
At the end of the task, the data is collated (pictures and csv comma delimited data), and zipped.
The send screen then connects to the ftp and uploads the file.
I am not sure how I could replicate such simplicity with the method you are describing above.
I just need to find a solution that is open for all mobile operators