Other carriers with high bandwidth plan

According to this article: https://help.hologram.io/en/articles/2093780-how-can-i-get-my-device-to-switch-networks-if-i-don-t-have-at-command-access

It is not possible to force a SIM to connect to any carrier EXCEPT for T-Mobile. However, in the Hologram dashboard, they have the option of connecting to T-Mobile only, or other carriers. Can I get some clarification?

Bump.

Are you asking if we have high bandwidth plans that cover multiple carriers? We do offer that.

The USA “All major carriers” plan includes TMobile inside it.

It seems like whenever I choose that plan, it NEVER chooses AT&T. It always defaults to T-Mobile which has bad signal (and the reason I upgraded to the better plan to begin with).