Firstly check that you have Mobile Data switched on.
If you are in a dead spot and cannot get a 3G or 4G signal you will get the following screen:
Just choose what you want to do (i.e Check-in or stop). Click on the relevant word and a box will pop up for you to enter your 4 digit pin. Your app will revert to the home screen once a connection has been reestablished, However, the app is still working in the background.
If you do respond via SMS/TXT it is recommended that you delete the
messages/conversation afterwards to protect your PIN number (The PIN number is
only used to respond to MyTeamSafe).
Please refer to the following guide: