Iridium GMDSS terminal, the Lars Thrane LT-3100S. Photo: Iridium Iridium Communications has started offering its real-time maritime emergency service, the company announced Tuesday. The service, Iridium Global Maritime Distress and Safety System (GMDSS), commenced operation on Dec. 11th, marking the culmination of years of work for Iridium. GMDSS is a safety of life system that helps rescue mariners in emergency situations while at sea. Iridium will now directly compete with Inmarsat as one of only two companies authorized to provide GMDSS services. Until now, Inmarsat has been the only provider GMDSS-approved satellite communication services since the inception of GMDSS in 1999.