if external cells are correctly defined, then it’s a mismatch between the BSC and the MSC.
ZTE -> external cells is not working, it means:
1/ either the iBSC does not manage to “contact” these cells -> HO COMMAND is not sent to the MS. HO is not triggered, there is no HO failure.
2/ the iBSC understands those cells are neighbors, a HO CMD is sent to the MS, but the MS cannot access the external cells. HO FAILURE occurs.
Which case is it ?
Case 1 i suppose ?
therefore you should perform an A INTERFACE trace. Do you see a HO REQUIRED from iBSC to MSC ?
do you see a HO REQUEST from MSC to target BSC ?
and so on…
find where is the “missing” message. If the HO REQUIRED is missing, it means the problem is in the iBSC.
if the HO REQUEST is missing, the problem lies in the MSC.
Initial check, before traces:
in OMCR ZTE, the external cells are defined
in MSC, the neighbor cells of iBSC are well defined.