this is a very very very common issue. Please don’t think I am being sarcastic or being a wise-a$$ : the problem is in the MSC !
Ask your NSS colleagues to double-check all the settings :
– are the external cells well defined ?
– are the external LAC well identified ?
This problem is always the same : HO inter MSC are not possible and yes, the MSC was already checked and all is good. And yet there is no HO… So …?
And the solution is always the same : “oh yeah, there was a mistake in the MSC definition… dammit !” 🙂
If you want to prove that the MSC is not doing its job, you just have to verify the following QoS counters :
from serving cell’s BSC :
how many HO REQUIRED are sent to the MSC ?
from the target cell’s BSC :
how many HO REQUEST are received from the MSC ?
If you obseve
“outgoing” HO REQUIRED = 1,000
“incoming” HO REQUEST = 0
–> Then it proves that the MSC is not forwarding the HO REQUIRED to the target BSC. It proves the MSC is not well-configured.
And if the counters show no problem then continue the same investigation : the target BSC should reply with the HO SUCCESSFUL [HO COMMAND] towards the MSC, and then MSC should forward the HO COMMAND to the serving BSC. Do the same comparison thanks to BSS counters.
Sometimes the HO works in one direction, but not in the other direction, it’s quite funny. But still, AFAIK, it is the MSC problem.