CSFB degraded in only one Frequency

Hi Experts,
CSFB Prep Success rate fine, but CSFB Exe Success rate degraded only for L900.
For L1800 both CSFBs are perfectly fine.

What would be the possible reason?

L2G neighbours added in L1800 whereas L900 only collocated neighbours added.

CSFB Exe Success rate =

Usually Execution failures are down to Target cell or technology.
So check if the target cell has no resource issues.

Target cells has no resources issues, because L1800 CSFB Exe success rate is 100% where same site L900 is 50%.

Neighbor’s does not hold much significance in CSFB.

Need to verify:

  1. 2G freq relation added
  2. Correct priority is defined for 2G