Mobile WiFi and fixed wireless devices that are certified have been tested by that carrier and are guaranteed by the carrier to work on their networks. Compatible devices meet the requirements of that carrier and should work on those networks.
The Nighthawk M6 (MR6150) is certified with AT&T and T-Mobile.
The Nighthawk M5 (MR5200) works best with AT&T and T-Mobile.
The Nighthawk M1 (MR1100) works best with AT&T and T-Mobile.
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