NTN-IoT ecosystem — Iridium, Skylo, AST SpaceMobile

Iridium — The Proprietary Incumbent

Iridium has operated a 66-satellite LEO constellation since the late 1990s, providing global voice and data including IoT services. Iridium's air interface is proprietary, predating any 3GPP NTN work. Their core IoT product, Short Burst Data (SBD), allows tiny telemetry messages over Iridium's low-bandwidth control channel. Iridium Certus, launched on the Iridium NEXT constellation, delivers higher data rates for vehicle terminals and broadband IoT. While not 3GPP, Iridium remains the dominant satellite IoT provider for maritime, aviation, polar regions, and government applications because of…