A SIM card is uniquely identified by its ICCID (serial number). SIM management systems (eg Jasper) will allow you to search for a SIM using this.
There are two places that this information is shown in our systems:
Click on the 'Details' link for the device:
On the details page the SIM ICCID is shown:
You can find the SIM ICCID on the 'Advanced' tab of the Asset.
This column is now also available on the "Asset List" report.