Abstract: According to a first aspect of the invention there is provided a method of providing a multi-IMSI solution for a subscriber having a mobile device in an operating mobile network, the mobile device being fitted with a SIM card having an IMSI and a baseband component, the mobile device comprising a corresponding baseband processor to enable the SIM card to communicate with a home network, run by a home network operator, related to the IMSI via the baseband processor. The method comprises fitting a SIM card overlay to the SIM card, the overlay acting as a proxy between the SIM card and the mobile device's baseband processor, the overlay comprising a primary (“pilot”) sponsor IMSI that is related to a sponsor network, run by a sponsor network operator, with a temporary activation Ki, determining when the mobile device has roamed out of the home network and into a foreign network having an agreement with a sponsor network associated with the sponsor IMSI.

Abstract: According to a first aspect of the invention there is provided a method of providing a multi-IMSI solution for a subscriber having a mobile device in an operating mobile network, the mobile device being fitted with a SIM card having an IMSI and a baseband component, the mobile device comprising a corresponding baseband processor to enable the SIM card to communicate with a home network, run by a home network operator, related to the IMSI via the baseband processor. The method comprises fitting a SIM card overlay to the SIM card, the overlay acting as a proxy between the SIM card and the mobile device's baseband processor, the overlay comprising a primary (“pilot”) sponsor IMSI that is related to a sponsor network, run by a sponsor network operator, with a temporary activation Ki, determining when the mobile device has roamed out of the home network and into a foreign network having an agreement with a sponsor network associated with the sponsor IMSI.