Globalstar doesn't support return messages. The Spot messengers have gotten less popular than Iridium ones partly because of that. Also, Globalstar has worse r

Globalstar doesn't support return messages. The Spot messengers have gotten less popular than Iridium ones partly because of that. Also, Globalstar has worse reception than Iridium which is why iPhone have to be waved around. Plus, Globalstar doesn't have worldwide coverage, they have coverage of most of continents but Pacific ocean and poles aren't covered. It is possible these new satellites will fix those limitations.