Various IMSIs are stored on your connect+ SIM card. These enable comprehensive network coverage.
The IMSI enables SIM cards to identify themselves uniquely in a roaming network. Your connect+ SIM card has up to 6 different IMSIs stored. This enables very broad worldwide network coverage at optimal prices. Different regions have different primary and secondary IMSIs. If a device such as a GPS tracker changes countries, an IMSI change can take place. If no connection can be established via the primary IMSI, a connection setup with the secondary IMSI is tested.
The IMSI change works in the interaction between SIM card and modem firmware
For the IMSI change to be successful, the modem must meet some requirements:
a) The device must proactively support the POLL INTERVAL and REFRESH parameters as specified by 3GPP: https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1807 . This must be applied when the SIM card changes IMSI.
b) The SIM needs at least 128 seconds for an IMSI change. A network search should take place on the device side for about 300 seconds before an IMSI change is initiated.
c) If no network connection is possible, the modem should not switch to an idle state or automatically reboot within 300 seconds.
If your end device does not meet these requirements, please contact your hardware manufacturer first. If implementation is not possible, please contact your wherever SIM sales partner.