So Mobi is actually a regional carrier/MVNO mix i suppose. They have their own network in HI apparently (from the former company, Coral Wireless, that re-branded to Mobi) and they partner with Verizon and others for (roaming/MVNO) coverage on the mainland.

I’m still researching if their agreements with Verizon are roaming agreements making them strictly a Regional Carrier (meaning customers not using the home network could be cut off) or if it is an MVNO style agreement, which would allow anyone to sign up anywhere in the US (not just HI).