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Whenever a re-election of GSM to LTE or WCDMA to LTE occurs, has a TAU occurred?


#1

Hi Everybody. Whenever a re-election of GSM to LTE or WCDMA to LTE occurs, has a TAU occurred?


#2

Hi Cesar,

The answer to your question is Yes.

After a re-selection (2G to 4G or 3G to 4G) occurs the TAU. Even after a CSFB (when LTE network does not support VoLTE and the mobile originate/terminate a call in 3G or 2G and then returns to LTE Network) TAU occurs. TAU is composed by:

  • Tracking area update request
  • Tracking area update accept
  • Tracking area update complete