Help with GPS, bluetooth, cellphone & SOS system

Hello Everyone!

Thank you for taking the time to read this and any input would be appreciated.

Ok, here are my thoughts and idea.
I ride motorcycles, I have ridden past anther rider that has gone down in a wooded median and stopped to help. He just had the wind knocked out of him and minor damage to the bike. But, here is the thing, I noticed him because I saw the fresh tire track in the mud and I look for other riders. There were all these cars going past but no one seemed to notice him at all! So, I am thinking of a way to automatically send like 5 text msgs and/or 5 phone calls on a bike that tips over for more than 3 seconds. The sensor is easy, heavily debounced tilt switches. Motorcycles lean over a good bit on turns and curves, bumps in the road can be jarring. So a sustain tilt as the trigger is a must.

Once triggered the Arduino should then, via Bluetooth, send text msgs with a text that says "Hey Fred's motorcycle fell over at GPS coordinates xxxx.xxxx xxxx.xxxx". Or plays a prerecorded audio file followed by the GPS data.

Later or as an option, I would like to use the GSM module to do it all but I want to know how much of this process can be assigned to the Arduino and how much to an app on the phone?

If you can point to sample modules or KB sections that would assist an old hardware tech in understanding it would be appreciated.

Thank you,
Chip