IMSI = International Mobile Subscriber Identity. This is a unique identifier that defines a subscriber in the wireless world, including the country and mobile network to which the subscriber belongs. It has the format MCC-MNC-MSIN. MCC = Mobile Country Code (e.g. 310 for USA); MNC = Mobile Network Code (e.g. 410 for AT&T), MSIN = sequential serial number. All signaling and messaging in GSM and UMTS networks uses the IMSI as the primary identifier of a subscriber.
The IMSI is one of the pieces of information stored on a SIM card.
MSISDN = Mobile Station ISDN number. This is the full phone number of a subscriber, including the national country code (e.g. 1 for US, 44 for UK, etc.). The purpose of the MSISDN is simply to allow a device to be called. A subscriber can have multiple MSISDNs (e.g. one phone number for business, one for personal calls, one for fax, etc.), but generally only one IMSI. The MSISDN does not need to be stored on the SIM card. In cases where it is stored on the SIM, the main reason is so that the user can use check to see what their own MSISDN is (in case they forget). The MSISDN is never signaled to of from the device.
ICCID = Integrated Circuit Card ID. This is the identifier of the actual SIM card itself - i.e. an identifier for the SIM chip. It is possible to change the information contained on a SIM (including the IMSI), but the identify of the SIM itself remains the same.
Thanks donieme. This post was helpful. Do you have a recommendation on which number should be used for tracking purposes? Of course we have our Serial Numbers for external tracking. Based on the info below, the IMSI and MSISDN could change, so the ICCID is the most consistent, reliable tracking number for the SIM. Is that accurate? Or is there another number that's not mentioned here? IMEI?
Thanks in advance.
I would use the ICCID for tracking purposes.The ICCID is printed on the SIM, and it also on the SIM carrier (the plastic part of the card) in barcode form. When a SIM is being inserted into a device (e.g. at a manufacturing or distribution center), it is common to first scan the SIM barcode and capture the ICCID, then scan the device serial number - this links the ICCID and device serial number in your system.
The IMEI is the unique identifier of the radio module itself, which you could also use for tracking purposes.
If you use the AT&T Control Center or the Rogers M2M Quicklink (both based on the Jasper platform) to manage your devices' wireless communications, you will see that the platform uses the ICCID as the default identifier, but you can use other tags too - such as device serial number, IMEI, etc.In other words, the platform allows you to use whatever identifiers you need to meet your business needs, which is pretty cool.