Have you tried putting that SIM into a phone ?
Where did you get the SIM from? They usually give you the associated phone number and you might have a locked sim so need to know the pin code
Describe how perfectly you connected and powered everything… that matters. A hand drawn schéma of how things are (not should be) goes a long way.. give a link to your module, which arduino are you using?…
Post the full code. Don’t post snippets (Snippets R Us!)
How is your serial console setup