Auto IMSI switch for international roaming
View Patent ↗The invention concerns a method for automatically switching from a Home IMSI to a Roaming IMSI and vice versa, said Home IMSI and Roaming IMSI being contained in a SIM card adapted to be used in a mobile station and adapted to comprise elementary files, wherein it comprises the step of triggering the switch from one IMSI to another when detecting an update of the elementary file comprising forbidden public land mobile networks (EF FPIMN ).
1. A method for automatically switching from a Home IMSI to a Roaming IMSI and vice versa, said Home IMSI and Roaming IMSI being contained in a SIM card adapted to be used in a mobile station and adapted to comprise elementary files including an elementary file containing a list of forbidden networks which may not be selected, also known as forbidden public land mobile networks file (EF FPLMN ), wherein the method comprises the step of triggering the switch from a first IMSI of the Home IMSI and Roaming IMSI to the other IMSI of the Home IMSI and the Roaming IMSI when detecting that the forbidden public land mobile networks file (EF FPLMN ) contains at least one network not corresponding to the first IMSI.
2. The method according to claim 1 , wherein the method comprises switching from the Home IMSI to the Roaming IMSI if the IMSI indicated in an elementary file containing a currently used IMSI (EF IMSI ) is the Home IMSI and if the forbidden public land mobile networks file comprises at least one Mobile Country Code different from a Mobile Country Code of the home network.
3. The method according to claim 1 , wherein the method comprises switching from the Roaming IMSI to the Home IMSI if the IMSI indicated in an elementary file containing a currently used IMSI (EF IMSI ) is the Roaming IMSI and if the forbidden public land mobile networks file comprises at least one Mobile Country Code of the home network.
4. The method according to one of the previous claims, wherein the method comprises clearing an elementary file comprising the last registered networks before proceeding to the switch.
5. The method according to one of claim 1 through 3 , wherein the method comprises clearing the file comprising the forbidden public land mobile networks after proceeding to the switch.
6. The method according to claim 5 , wherein the method comprises updating a file which comprises the preferred networks.
7. The method according to claim 5 , wherein the method comprises initializing the SIM card.
8. A subscriber Identity Module adapted to be used in a Mobile Station comprising a Home IMSI and a Roaming IMSI, elementary files including an elementary file containing a list of forbidden networks which may not be selected, also known as forbidden public land mobile networks file (EF FPLMN ), comprising an application causing the subscriber identity module to switch from a first IMSI of the Home IMSI and the Roaming IMSI to the other IMSI of the Home IMSI and the Roaming IMSI the subscriber identity module further comprising programming to cause the subscriber identity module to trigger the switch from the first IMSI to the other IMSI when detecting that the forbidden public land mobile network file (EF FPLMN ) contains at least one network not corresponding to the first IMSI.
9. The subscriber Identity Module of claim 8 further comprising programming to cause the subscriber identity module to switch from the Home IMSI to the Roaming IMSI if the IMSI indicated in the elementary file containing a currently used IMSI (EF IMSI ) is the Home IMSI and if the forbidden public land mobile networks file comprises at least one Mobile Country Code different from a Mobile Country Code of the home network.
10. The subscriber Identity Module of claim 8 further comprising programming to cause the subscriber identity module to switch from the Roaming IMSI to the Home IMSI if the IMSI indicated in an elementary file containing a currently used IMSI (EF IMSI ) is the Roaming IMSI and if the forbidden public land mobile networks file comprises at least one Mobile Country Code of the home network.
11. The subscriber Identity Module of claim 8 , 9 or 10 further comprising programming to cause the subscriber identity module to clear an elementary file comprising the last registered networks before proceeding to the switch.
12. The subscriber Identity Module of claim 8 , 9 or 10 further comprising programming to cause the subscriber identity module to clear the file comprising the forbidden public land mobile networks after proceeding to the switch.
13. The subscriber Identity Module of claim 12 further comprising programming to cause the subscriber identity module to update a file which comprises the preferred networks.
14. The subscriber Identity Module of claim 12 further comprising programming to cause the subscriber identity module to initialize the SIM card.