and used the SIM card for 20-hours of eye-watering phone calls.
The way this usually works is that the miscreant(s) are working in combination with an operator of a premium line in one of the countries in Africa and/or around the Carribean. Stolen SIMs and stolen VOIP credentials are loaded into a dialer and the bill gets to eyewatering levels in seconds.
That is where the 20 hours of non-stop calling come from. I suspect the stork(s) were targeted specifically because someone knew that the trackers contain a SIM.