Sandra,
The application currently provides feedback about whether their forms have been submitted to the server. In our experience receiving an abundance of text messages is not the most effective feedback that users can receive of their progress, since it clogs up the phone's text message management system.
Have you considered using automated messages in somewhat the opposite way? Our research has shown that the most effective strategy for text message communication is to send reminders for workers about cases that haven't received a followup in a while to remind them to either perform a visit or report a reason for not visiting, which can be helpful centrally. It also lets the user use the normal, passive mechanisms to know when things are going well, and only receive active, directed mechanisms to notify them when something is amiss.
Regards,
-Clayton