Chapter 4 FortiOS Carrier : GTP identity filtering : Configuring IMSI filtering in FortiOS Carrier
  
Configuring IMSI filtering in FortiOS Carrier
In many ways the IMSI on a GPRS network is similar to an IP address on a TCP/IP network. Different parts of the number provide different pieces of information. This concept is used in IMSI filtering on FortiOS Carrier.
To configure IMSI filtering go to Security Profiles > Carrier > GTP Profile and expand IMSI filtering.
While both the APN and MCC-MCN fields are optional, without using one of these fields the IMSI entry will not be useful as there is no information for the filter to match.
 
Enable IMSI Filter
Select to turn on IMSI filtering.
Default IMSI Action
Select Allow or Deny. This action will be applied to all IMSI numbers except as indicated in the IMSI list that is displayed.
The default value is Allow.
APN
The Access Point Number (APN) to filter on.
This field is optional.
MCC-MNC
The Mobile Country Code (MCC) and Mobile Network Code (MNC) to filter on. Together these numbers uniquely identify the carrier and network of the GGSN being used.
This field is optional.
Mode
Select the source of the IMSI information as one or more of the following:
Mobile Station provided - the IMSI number comes from the mobile station the mobile device is connecting to.
Network provided - the IMSI number comes from the GPRS network which could be a number of sources such as the SGSN, or HLR.
Subscription Verified - the IMSI number comes from the user’s home network which has verified the information.
While Subscription Verified is the most secure option, it may not always be available. Selecting all three options will ensure the most complete coverage.
Action
Select the action to take when this IMSI information is encountered. Select one of Allow or Deny.
Delete Icon
Select the delete icon to remove this IMSI entry.
Edit Icon
Select the edit icon to change information for this IMSI entry.
Add IMSI
Select to add an IMSI to the list. Not active while creating GTP profile, only when editing an existing GTP profile.
Save all changes before adding IMSIs. A warning to this effect will be displayed when you select the Add IMSI button.
Also see “Basic filtering options”.