gm862-gps project question - interrupts?

GPS/GNSS Development Boards
1

I have the GM862-GPS module with the USB evaluation kit. I need to make a child-tracking type device for a school project. It has 2 modes:

  1. Normal mode: send location every 20 minutes

  2. Emergency mode: send “constant” GPS data while on a voice call

Emergency mode needs to be activated by either hitting a button attached to the module, or by calling the module from a “parent” phone. I can send location and whatnot, but I cannot figure out how to start emergency mode. I would like the module to be in power-saving mode between the 20 minute updates, but when it receives a call or its button is pressed, it will activate this emergency mode script. Is there any way to implement an interrupt-type event to achieve this?