SRVCC preparation failure

Hello Experts.
For SRVCC to GSM at what nodes we have to define in the legacy network?
I m getting SRVCC preparation failure due to Destination preparation failure.

Check target cell CGI it all are correct and live.
If inter site distance is high then tune b2 thresholds.

Which are the nodes need to check?
Checked at EnodeB and GCS. At both end it’s correct only.

Srvcc preparations fail for particular relation?

All the relations.

Check in any change in LAC for iRAT neighbours.

How much is ur B2 thrsh 1&2? And offsets?

No change in LAC, after PLMN changed issue started.

Vendor?
Check Which type of SRVCC the eNodeB initiate.
For Huawei, the eNodeB can initiate a CS and PS SRVCC procedure or eNodeB can initiate CS-only. If MME or the RNC doesn’t support you can set only for CS (CsPsHOInd false).

Vendor is ZTE, and its initiate only CS handover.

Check:
Retry and penalty…

As far as I know, SRVCC HO indication only impact on SRVCC execution instead of preparation.

Was there any other action/changes on the Core?
Like MGW migration to Open MGW or else?

No, there wasn’t any other changes.

The basic concept to SRVCC to happen…

  1. the feature state should be activated on eNodeB (SRVCC handover to GERAN) and
  2. VoicePriority should be enabled from LTE to GSM frequency.

Handover Routing is one point can be checked at CORE.