How to know sim card type(4G?3G?)

How to know sim card type?
Can I send commands to know that?

Hi @shen-huanjie,
there is no easy way to determine if the SIM is 3G or 4G , except may be by checking specific file into the SIM which can only be dedicated to a 4G sim.

You need to identify the file thanks to 3GPP specification , then by using at+csim or at+crsm you can try to access that file.

Usually the user wants to know if their SIM has a subcription for 3G or 4G , and only their network operator can answer to that.

Anyway this has nothing to do with Legato.

Do you have a specific use case ? what is the purpose of your request?