Overcoming VoLTE Call Failure

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

Disabled - Configuration Required

Related Changes in This Release

Not Applicable

Related Documentation

  • Command Line Interface Reference

  • MME Administration Guide

  • Statistics and Counters Reference

Revision History

Revision Details

Release

First introduced.

21.20.28

Feature Description

During the Create Bearer Request (CBR) process, eNB receives ERAB Modification Indication before receiving Dedicated Bearer Accept and this suspends the CBR process. The S1 response flag was set to zero during the process when CBR got suspended.

The CBR process is resumed only after receiving ERAB Modification Confirmation. Before sending the CBR response, S1 response flag is checked, which is set to zero. Due to this, the CBR gets rejected as the dedicated bearer response is not received for the bearer.


Note

The S1 response flag is set when Dedicated Bearer Accept is received from UE.

To overcome this, the flag must not be set to zero when suspending the received bearer S1 response. If S1 response is received, the flag and S1 request are set to 1 (TRUE).