I use a Spot Gen3 so SWIMBO can keep an eye on where I am when I go for a ride. Helps put her mind at ease if she can just click on a link and check that I'm still moving.
It's programmed to send a specific message via text and email when I hit the button, but is also continuously updating my current location (mine is currently set to ping my location at 5 minute intervals), and it's GPS based, so it works when not in mobile phone range.
If you want to see a real time demonstration, this link will become active at
Midday Thursday 14/5/15 until Monday PM 18/5/15-
https://spotwalla.com/tripViewer.php?id=d16755505c31bac3bOrange line = my travel path
Orange dot = my location when pinged at 5 minute intervals
Green Pin = my pre-programmed check-in / OK message
Yellow Pin = My pre-programmed specific message
Red Pin = I'm in trouble and need help (hope you don't see that one)
Cheers, hope the link works.