Operator Policy Selection Based on IMEI-TAC

Feature Description

Operator policies (proprietary Cisco functionality) empower the carrier/network operators to configure preferred call handling practices. Also, operator policies can be configured to determine the granularity of the implementation: to groups of incoming calls or simply to one single incoming call. The purpose, use, and configuration of operator policies is outlined in the Operator Policy chapter elsewhere in this guide.

Based on the configuration (see Configuring Operator Policy Based on IMEI-TAC), the MME will select / re-select the operator policy whenever the MME retrieves the IMEI or IMEI-SV in one of the following scenario:

  • normal 4G Attach when the IMEI/IMEI-SV is retrieved via Identity-Request with IMEI.
  • normal 4G Attach when the IMEI/IMEI-SV is retrieved via Security-Mode-Complete (policy attach imei-query-type under MME service must be enabled).
  • normal 4G TAU when the IMEI/IMEI-SV is retrieved via Security-Mode-Complete (policy tau imei-query-type under MME service must be enabled).
  • inbound handover when IMEI/IMEI-SV is received with IMSI via the Forward-Relocation-Request.
  • S10 and S3 Attaches when IMEI/IMEI-SV is retrieved with IMSI via EGTP-Identification-Request.
  • Inter-RAT TAU and Intra-RAT TAU with MME change when IMEI/IMEI-SV is received with IMSI in Context-Response.

Selection Based on IMEI-TAC

With Releases 18.5 and higher,"Operator Policy Selection Based on IMEI-TAC" enables the MME to selects / re-select an operator policy for call handling based on the user equipment's (UE's) unique international mobile equipment identity - type allocation code (IMEI-TAC) rather than the normal selection method, which is based on the UE's international mobile subscriber identity (IMSI) and PLMN-ID. The IMEI number is assigned to a mobile device or user equipment (UE) by the manufacturer. The network uses the IMEI to identify if devices are valid.

Including the type allocation code (TAC) in the operator policy selection process supports network access restrictions being applied to UEs based on the type of wireless device identified by the IMEI-TAC. The TAC, the first eight digits of the 15-digit IMEI or 16-digit IMEI-SV, identifies the equipment manufacturer, the wireless device type and the model number (if there is one); for example, TAC of 35201906 identifies an Apple iPhone 5S.

IMEI-TAC Groups

With Release 18.6 and higher, the MME supports configuration of up to 25,000 IMEI-TAC, up from the original number of 1024 IMEI-TAC per MME. As well, these IMEI-TAC can be configured in groups listing individual IMEI-TAC and/or organized in ranges of IMEI-TAC. Up to 50 IMEI-TAC groups can be configured per MME and once an IMEI-TAC group is created, each group can be configured with up to 500 unique IMEI-TAC values and/or up to 20 IMEI-TAC ranges - which can overlap. For command details, refer to the Configuration section below.

Granular Selection Options for IMEI-TAC: MCC/MNC, MSIN, PLMNID

With Release 19.4 and higher, the operator is allowed more granular control of configuration for operator policy selection. Besides operator policy selection based on IMEI-TAC of the UE, the operator can optionally configure selection based on:
  1. IMEI-TAC only,

  2. IMEI-TAC + Service PLMNID,

  3. IMEI-TAC + MCC-MNC of UE,

  4. IMEI-TAC + MCC-MNC of UE + Serving PLMNID,

  5. IMEI-TAC + IMSI,

  6. IMEI-TAC + IMSI + Serving PLMNID,

The MME uses this configuration to select the operator policy whenever it retrieves the IMEI/IMEI-SV from either a UE or a peer for all non-emergency calls.

How It Works

Based on the configuration (see Configuring Operator Policy Based on IMEI-TAC ), the MME will select / re-select the operator policy whenever the MME retrieves the IMEI or IMEI-SV in one of the following scenario:

  • normal 4G Attach when the IMEI/IMEI-SV is retrieved via Identity-Request with IMEI.

  • normal 4G Attach when the IMEI/IMEI-SV is retrieved via Security-Mode-Complete ( policy attach imei-query-type under MME service must be enabled).

  • normal 4G TAU when the IMEI/IMEI-SV is retrieved via Security-Mode-Complete ( policy tau imei-query-type under MME service must be enabled).

  • inbound handover when IMEI/IMEI-SV is received with IMSI via the Forward-Relocation-Request.

  • S10 and S3 Attaches when IMEI/IMEI-SV is retrieved with IMSI via EGTP-Identification-Request.

  • Inter-RAT TAU and Intra-RAT TAU with MME change when IMEI/IMEI-SV is received with IMSI in Context-Response.

Supported Options

With this feature, the MME supports location-based restriction based on the IMEI-TAC. The MME Service configuration must include settings to instruct the MME to retrieve/query the IMEI/IMEI-SV for Attach and TAU. Refer to Configuring Policy Selection for Normal 4G Attach/TAU.

Restrictions

For all emergency calls, the MME selects the emergency profile and not an operator policy based on IMEI-TAC configuration.

Currently, the MME allows a maximum of 1024 associations of operator policy to the key where the key can be any of the following: IMSI, SERVICE PLMN-ID, SSI-ID, Domain, IMEI-TAC and ALL.

Configuring Operator Policy Selection Based on IMEI-TAC

There are multiple components involved in the configuration of this feature. We recommend that for first time feature configuration, you perform the configurations in the order in which they are presented below.

Configuration of this feature makes use of many previously existing commands and keywords. Only new or modified commands and keywords are explained in detail in this document.

Configuring the Operator Policy(s) and Call Control Profile(s)

We recommend that you first configure the operator policy and call control profile and make a note of the names you assign the policy and profile.

configure 
   operator-policy name policy_name 
      associate call-control-profile name profile_name 
      exit  
   call-control-profile name profile_name 
      end 

Notes:

  • For information about these commands and keywords, refer to the Command Line Interface Reference.

Configuring Policy Selection for Normal 4G Attach/TAU

To enable the MME to retrieve the IMEI from the UE, the following MME service configuration is required. The following configures the Operator Policy selection based on IMEI-TAC for normal 4G Attach or normal 4G TAU when the IMEI/IMEI-SV is retrieved via Security-Mode-Complete. After the operator policy and call control profile are configured, then perform the additional configuration of the imei-query-type for the MME service.

configure 
 context context_name 
      mme-service name service_name 
         policy { attach | tau } imei-query-type { imei | imei-sv } verify-equipment-identity [ allow-on-eca-timeout | deny-greylisted | deny-unknown | verify-emergency ]   
         end 

Notes:

  • The command listed above are not new for this feature. For information about these commands and keywords, refer to the Command Line Interface Reference.

Configuring IMEI-TAC based Selection of the Operator Policy


Important

The operator policy(s), call-control profile(s), and IMEI-TAC group(s) need to be configured already and according to the instructions above.


To setup IMEI-TAC-based operator policy selection, use the precedence command in the LTE Subscriber Map configuration mode to:

  • set the order of precedence for the subscriber map,

  • set which type of matching criteria is to be used to determine which operator policy to select - for this procedure, use the imei-tac keyword,

  • optionally, set more granular IMEI-TAC matching criteria, either singly or in pairs:

    • mcc + mnc

    • imsi

    • service-plmnid

  • point to an operator policy for subscribers meeting the match criteria.


Important

The following example details configuration for IMEI-TAC-based selection. Other match criteria options are not included here. For more information on configuration options, refer to the Command Line Interface Reference.


configure 
   lte-policy 
      subscriber-map map_name 
         precedence precedence_number match-criteria imei-tac group group_name [ imsi mcc mcc mnc mnc 
[ msin { first start_msin_value last end_msin_value } ] ] [ operator-policy-name policy_name 
         no precedence precedence_number 
         end 

Notes:

  • precedence precedence_number - The precedence level defined by the operator is used to resolve the selection of the operator policy when multiple variable combinations match for a particular UE. The lower precedence number takes greater priority during selection.

    In releases prior to 21.8: precedence_number must be an integer from 1 to 1024.

    In 21.8 and later releases: precedence_number must be an integer from 1 to 10000, where 1 has the highest precedence.

  • match-criteria - Selects which set of variables will be 'matched-to' to select an operator policy. For this procedure, use the imei-tac keyword to select the IMEI-TAC group as the matching criteria. For more granular match criteria, include the following singly or in pairs: IMSI and/or MCC+MNC and/or serving PLMNID in accordance with the following usage options:

    • Operator policy selection based on IMEI-TAC only, syntax example:

      precedence 1 match-criteria imei-tac-group myGroup operator-policy-name BESTpol 
    • Operator policy selection based on IMEI-TAC + Service PLMNID, syntax example:

      precedence 1 match-criteria imei-tac-group myGroup service-plmnid 12345 
       operator-policy-name BESTpol 
      
      
    • Operator policy selection based on IMEI-TAC + MCC-MNC of UE, syntax example:

      precedence 1 match-criteria imei-tac-group myGroup imsi mcc 123 mnc 234 operator-policy-name BESTpol 
      
      
    • Operator policy selection based on IMEI-TAC + MCC-MNC of UE + Serving PLMNID, syntax example:

      precedence 1 match-criteria imei-tac-group myGroup imsi mcc 123 mnc 234 service-plmnid 56789 operator-policy-name BESTpol 
      
    • Operator policy selection based on IMEI-TAC + IMSI, syntax example:

      
      precedence 1 match-criteria imei-tac-group myGroup imsi mcc 123 mnc 234 msin first 1223 last 2333 operator-policy-name BESTpol 
      
    • Operator policy selection based on IMEI-TAC + IMSI + Serving PLMNID, syntax example:

      
      precedence 1 match-criteria imei-tac-group myGroup imsi mcc 123 mnc 234 msin first 1223 last 2333 service-plmnid 56789 operator-policy-name BESTpol 
      
  • group group_name - Identifies the name of the previously-defined IMEI-TAC group with the configured IMEI-TAC values to use for matching. The group name is a string of 1 through 64 alphanumeric characters.

  • operator-policy-name policy_name - Configures the name of the operator policy to which selection should be pointed after the criteria matching is completed. The policy name is a string of 1 through 63 alphanumeric characters.

  • For more information about the lte-policy , subscriber-map , and the precedence commands, refer to the LTE Subscriber MAP Configuration Mode chapter in the Command Line Interface Reference .

Verifying the Configuration

From the Exec mode, use the following to verify the configuration for operator policy selection based on IMEI-TAC:

show configuration  

The following is an example of the type of information that would be presented in the show output:

config 
... ... ... 
  lte-policy 
    subscriber-map submap1 
      precedence 1 match-criteria imei-tac group itacgrp1 operator-policy-name oppol1 
      precedence 2 match-criteria imei-tac group imeitacgrp11 service-plmnid 12345 operator-policy-name op2 
      precedence 3 match-criteria imei-tac group imeitacgrp2 operator-policy-name op1 
    exit 
    imei-tac-group itacgrp1 
      tac 31441551 77777777 87650506 87654321 
      tac-range from 23456789 to 98765432 
    exit 
    imei-tac-group imeitacgrp11 
      tac 01192119 66666666 87650999 98765432 
      tac-range from 11001100 to 11111111 
….. … …. 
    exit 
... ... … 
end 

Monitoring and Troubleshooting the Operator Policy Selection Based on IMEI-TAC

Verify Configuration

Use the following show commands to verify the configuration to ensure that it is correct:
  • show operator policy full { all | name policy_name }

  • show call-control-profile full { all | name profile_name }

  • show mme-service name service_name

  • show lte-policy subscriber-map name map_name

  • show lte-policy imei-tac-group summary

  • show lte-policy imei-tac-group name group_name