What are an IMSI and an ICCID?¶

An IMSI identifies a mobile subscription to the network. An ICCID is the serial identifier of the physical SIM card or eSIM profile carrying subscription authority. They are related but not interchangeable.

Use each identifier for its own object¶

A SIM replacement commonly changes the ICCID while the number and subscription continue. Provider, account or network changes can also affect IMSI associations.

Preserve both values exactly as text with their original field names, source, provider and dates. Use provider records to map IMSI, ICCID, telephone number and subscriber at the relevant time, especially across swap, replacement, port and eSIM events.

Link subscription to equipment and person¶

Compare the subscription values with IMEI device records to establish which handset used them and when. Retain disagreements until timing, transfer or collection explains them.

Neither value identifies the human user. Device possession, access, location and communication evidence supply that separate link.