What is an IMSI?
Datamobile Multi-IMSI SIMs are configurable with multiple IMSI so they can always connect to the best available network operator.
The International Mobile Subscriber Identity (IMSI) is used in GSM, UMTS and LTE mobile networks to uniquely identify network subscribers (internal subscriber identity). In addition to other data, the IMSI is stored on a special chip card, the SIM (Subscriber Identity Module). The IMSI number is awarded worldwide by the mobile network operators once per SIM. The IMSI has nothing to do with the telephone number assigned to the SIM card.
The IMSI consists of a maximum of 15 digits and is composed as follows:
- Mobile Country Code (MCC), 3 digits
- Mobile Network Code (MNC), 2 or 3 digits
- Mobile Subscriber Identification Number (MSIN), 1-10 digits
When a connected device is turned on, it performs authentication with the network. This authentication method uses the IMSI as the key to the network. This query occurs at the beginning of each data session.
Network operators have a defined list of IMSI allowed to connect to their network. The list of allowed IMSIs is negotiated in roaming agreements between providers.
What is Multi-IMSI?
Standard SIM cards usually have an IMSI because they are powered by a network. In contrast, Multi-IMSI SIMs have more than one IMSI. Therefore, if needed, another home network can be selected. An MSISDN (telephone number) can be assigned to multiple IMSIs. Updates are possible over-the-air (OTA).
Advantages of a Multi-IMSI solution
The main problems with using a single IMSI are:
- Lack of coverage
- Roaming network error
- Error in the home network
Multi-IMSI SIMs are specifically designed for roaming and remote applications that require maximum signal handling, multiple networking options, and robust failover connectivity for network problems. If the first configured IMSI does not find a roaming partner, an IMSI switch occurs, with the second IMSI attempting to connect to the available providers.