An ICCID (Integrated Circuit Card Identifier) is a 19 or 20-digit serial number that acts as the unique identifier for a physical subscriber identity module (SIM card). Unlike an IMEI, which is permanently tied to the phone's hardware, the ICCID belongs exclusively to the removable plastic chip and links to your personal billing account and phone number.
A common misconception is that a SIM card has an IMEI number; it does not. When you move a SIM card between different handsets, your ICCID and phone number follow you, while the 15-digit IMEI hardware identity remains permanently fused to the specific phone chassis you left behind.
