Iridium and T-Mobile are scaling satellite-delivered positioning, navigation, and timing services under a U.S. Department of Transportation initiative to bolster the resilience of 5G networks against GPS disruptions. The collaboration equips T-Mobile sites with Iridium PNT receivers to deliver precise, authenticated timing that complements existing GNSS sources. Iridium transmits timing over its low-earth-orbit constellation in the L-band, offering weather-resilient coverage and stronger signals than typical GNSS. The service is engineered for sub-100-nanosecond accuracy, uses cryptographic protections for integrity, and can operate indoors without an external antenna, addressing urban canyons, indoor small cells, and hard-to-reach sites where GNSS is unreliable.