Are you able to test the SIM card in another device to confirm if you see the same issue. If the SIM works without issue, your device may be the issue. What kind of device are you using?If the SIM card does not work in another device, I would suggest...
Couple thoughts come to mind with the FE to FE SMS delay and @Charliethecat issue. Are you both using the same messaging app?You can confirm by opening your Settings, scroll down and touch Apps. You should see "Choose default apps" at the top of the ...