Locking a module to a particular SIM

I am looking for a way to lock my OpenAT app to the provided SIM - ie I don’t want someone to replace my SIM with their own. So i’ve been looking for a way to read some unique ID parameters from the SIM but can’t find anything. Does anyone have any ideas ?

AT+CCID gives the unique SIM “Serial Number”

Yes it does! How did I miss that! I’ve been staring at these massive documents for too long I think. Thanks again for your help