Hello,
Thank you for contacting us.
By default, your given command have two outputs: OK or Disabled.
This is the reason, why you receive OK message even with the removed SIM card.
In order to run some custom commands, you will need package named luci-app-commands.
You could install this package using SSH or CLI with commands:
opkg update
opkg install luci-app-commands
After this package are installed, your will find a new section named Custom commands in System drop list.
Using this, you could create your own custom commands.
In order to receive information about mobile connectivity, I advice to use /usr/sbin/gsmctl with parameter you want to receive.
If there will be any question, please inform.
Best regards,
Sigitas K.