Method and system for roaming of a mobile communications unit

摘要

A method for use when a mobile communication device roams between a home network and foreign networks, which device includes a SIM card using an IMSI, includes the steps of storing on the SIM card a first IMSI for network identification; upon receipt of a location update message indicating that the mobile device has moved to a first visited network, firstly causing the HLR to send an instruction message to the mobile device to change, to a second IMSI, the IMSI used for network identification; secondly causing the mobile device to use the second IMSI for network identification and saving the first IMSI; and then causing the mobile device to perform a device network refresh; and upon roaming back to the home network, causing the mobile device to change the IMSI used for network identification back to the first IMSI and then to update its network status.

主权项

1. A method for roaming of a mobile communication device between a mobile communication home network in a home country and one or several mobile communication networks in one or several visited countries, which mobile communication device comprises a Subscriber Identity Module (SIM) card identifying itself to each network using an International Mobile Subscriber Identity (IMSI), wherein the method comprises the steps of
a) storing on the SIM card a first IMSI and using it for network identification of the SIM card; b) upon receipt of a location update message indicating that the mobile device has moved from the coverage area of the home network to the coverage area of a first visited network in a first visited country, firstly causing the home network to send an instruction message over the air to the mobile device to change the IMSI used for network identification of the SIM card to a second IMSI which is associated with the HLR (Home Location Registry) of a first collaborating mobile communication network in the first visited country; secondly causing the mobile device to store the second IMSI on the SIM card and to use it for network identification of the SIM card and in addition to save the first IMSI and then causing the mobile device to perform a device network refresh; c) causing the mobile device to detect a roaming of the mobile device from the coverage area of the first collaborating network to the coverage area of a second visited network in a second visited country; d) upon detection of such roaming activity, causing the mobile device to change the IMSI used for network identification of the SIM card back to the first IMSI and then to perform a device network refresh, whereupon firstly, upon the receipt of the location update message resulting from the change of IMSI used for network identification, the home network is caused to send an instruction message over the air to the mobile device to change the IMSI used for network identification of the SIM card to a third IMSI which is associated with the HLR of a second collaborating mobile communication network in the second visited country; secondly causing the mobile device to store the third IMSI on the SIM card and use it for network identification of the SIM card while in addition saving the first IMSI and then causing the mobile device to perform a device network refresh; and e) upon roaming back to the coverage area of the home network, causing the mobile device to change the IMSI used for network identification of the SIM card back to the first IMSI and then to perform a device network refresh.