IMSI Filter Length Extension

A GPRS support node (GSN) identifies a Mobile Station (MS) by its International Mobile Subscriber Identity (IMSI). An IMSI consists of three elements: the mobile country code (MCC), the mobile network code (MNC), and the Mobile Subscriber Identification Number (MSIN). The MCC and MNC combined constitute the IMSI prefix and identify the mobile subscribers home network or public land mobile network (PLMN). By setting IMSI prefixes, you can configure the device to deny GPRS tunneling protocol (GTP) traffic coming from nonroaming partners. By default, a device does not perform IMSI prefix filtering on GTP packets. This feature extends the length of the IMSI filter length from 5 or 6 digits to 15 digits, which is the full length for the IMSI filter. You can set the IMSI prefix as a wildcard character (*) or enter any digit from 0 to 9.