What provider does Sidekick or Duo use?

[Bubbanc]

My provider swapped out my dying 3G for a 4G Verizon Honeywell unit. I’ve had at least 4 outages in the past 6 months where the long range radio warning comes up and beeps. This is annoying when I’m home, but really annoying when a house sitter has to deal with it. I’m ready to ditch my provider and go all in with Eyez-On given I already have an EVL4. I did read on the website that it will switch if the provider goes down (like happened with Rogers). Any feedback on this would be great.

[GrandWizard]

In the US it uses AT&T as the primary carrier, with T-Mobile and Verizon as roaming secondaries if no AT&T cell is present.