What should be normal call setup time 4G to CSFB 2G?

4G LTE
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1

Hi All,
What should be normal call setup time 4G to CSFB 2G/3G?

2

It shouldn’t be more than 2 seconds.

3

Less than 3 sec.

4

Found this also… 5 sec E2E.

5

Is there anything you can recommend to reduce the call setup time in CSFB by 5 seconds?