Determining GUTI Type using Earlier GUTI Type IE

Feature Summary and Revision History

Summary Data

Applicable Product(s) or Functional Area

MME

Applicable Platform(s)

  • ASR 5500

  • VPC-DI

  • VPC-SI

Feature Default

Enabled - Always On

Related Changes in This Release

Not applicable

Related Documentation

MME Administration Guide

Revision History

Revision Details

Release

First Introduced

21.20.3

Feature Changes

According to the 3GPP specification 23.401, the MME resolves the old MME/SGSN using Globally Unique Temporary Identity (GUTI) sent earlier in the Attach request and TAU request messages, and determines if the earlier GUTI is mapped or native by one of the following two methods:

  • Indication using most significant bit (MSB) in MME Group ID.

  • Explicit indication sent from UE to MME (Old GUTI type IE).

Previous Behavior: MME used the MME Group ID MSB bit to determine the GUTI type for the UEs moving from old MME or SGSN.

New Behavior: MME uses the old GUTI type IE to determine the GUTI type for the UEs moving from old MME/SGSN/AMF. If old GUTI Type IE is not present, then MME uses MME Group ID MSB bit to determine the GUTI type.