If you update to the latest modem firmware, and your hotspot goes deaf.. Here's why. IMHO This is a great move by the development teams as some operators 1. don't know they're interfering, and 2. some could care less.. (My stuff works, who cares)
As of firmware ZUMspot/MMDVM_HS v1.4.12, 435.0 - 438.0 and 145.8 - 146.0 have been blocked because they are used internationally for satellite communication, which can be (and have been lately) disrupted by low power hotspot transmissions.