No, you don't, but you will need a data SIM from your cell phone provider, and that has a monthy charge.  Some other services force you to pay every month for them to monitor their device.  With our device you are instantly notified via your cell phone that something has happened, and you can turn on immediate chat to speak with them.

Getting the watch or the pendant takes a little time to set up.  you will need to program the numbers to call in an emergency and install the application on your mobile phone so that you can monitor the device.  All of this should take about 10-15 minutes.  After that, there is nothing to do.  You can check on the status of the device any time you want using the app.

Like anything electronic, it won't work if the batter dies.  Before that happens though, both the wearer and you will be notified that the battery is getting low, and you can always check on the battery level at any time using the mobile app.

Geofencing is exactly what it sounds like -- it is a geographic virtual fence around an area.  For example, you might program a 100 yard geofence around the wearer's house.  Whenever they get further away from the house than 100 yards, you will get an alert.  You set up geofences inside of the mobile app, and its easy.  You just point to a place on the map and tell it the diameter of the circle you want around that point.

Our devices use the cellular phone system to communicate with the mobile application that you will run on your mobile phone.  If the device is in an area where there is no cell phone coverage, then it will not be able to alert you to any events.  Of course, you can see the history of the device up to the point where it lost coverage, and you will also get an alert when it loses coverage.

Nobody actually asked this.  We just thought we would add it for fun.

But to answer the question: Yes!  This can be used while skydiving!