Patent ID: 8175589

Claim:
A method for SIM card replacement, aimed to obtain the functionality of a first SIM card storing a real IMSI number associated to a real MSISDN, the method comprising: providing a user with a replacement SIM card storing a fake IMSI number; associating the fake IMSI number with a fake MSISDN; setting unconditional call forwarding of all incoming calls aimed to the real MSISDN to the fake MSISDN; wherein the method further comprises: replacing the calling party number with the real MSISDN for each call originated from a calling mobile station using a replacement SIM card; wherein the method further comprises: defining in all the S-CSCF a trigger rule to determine an AS associated to the fake MSISDN; determining, in said AS, the real MSISDN associated to the fake MSISDN; and wherein the replacement of the calling party number with the real MSISDN, for each call originated from a calling mobile station using a replacement SIM card, is carried out by: obtaining from the mobile station an ISUP IAM message with the calling party number and the destination number; converting the IAM message into a SIP message; sending said SIP message to a S-CSCF; obtaining, by means of the defined trigger rule, the AS associated with the calling party number; obtaining the real MSISDN associated to the fake MSISDN; replacing the calling party number, with the real MSISDN.