What identifiers might I find on a mobile device?¶
A mobile device can contain several identifiers, and each one answers a different question.
What this means¶
The most common mistake is to see an identifier and assume it identifies the person using the device.
A handset may have an IMEI, which identifies the device hardware for mobile-network purposes. It may also have a serial number assigned by the manufacturer.
A SIM or eSIM is linked to separate identifiers. These can include an IMSI, which identifies the mobile subscription to the network, and an ICCID, which identifies the SIM profile or card.
The device may also show one or more telephone numbers, but a number can move between SIMs, devices and network providers.
Wi-Fi and Bluetooth functions have their own hardware addresses. These may help connect a device to network or pairing records, although modern devices may use randomised addresses in some situations.
Applications and device accounts introduce more identifiers. These may include usernames, email addresses, account IDs, advertising IDs, push-notification tokens, cloud-device IDs and app-specific installation identifiers.
Some identifiers remain stable for a long time. Others change after a reset, reinstall, software update, account change or privacy setting.
Their real value comes from linking evidence sources.
An IMEI may connect a handset to network records. An ICCID may connect a SIM to a subscription. An app account ID may connect provider records to activity seen on the device. A serial number may confirm that a seized handset is the same item shown in purchase or repair records.
The operational takeaway is: treat identifiers as links between devices, subscriptions, accounts and records. Use them to build attribution, but do not treat any single identifier as proof of the human user.
Evidential limits¶
It usually does not.
Record identifiers exactly and note where they came from. A number shown in device settings is not the same as one supplied by a network provider. A label on the casing may not reflect the currently fitted hardware or profile.