It’s quite difficult to find 3GPP references for such scenario, but now i understand your problem better. Thanks for correcting my previous post.
Let me recap :
(1) Before the MM state is established, the MSC must send the paging on the whole LAC. The paging should result as a failure on CN side.
(2) When MM state is established, the MSC can send the paging to the cell directly, and “ping” the MS with the FACCH.
Your problem is in the phase (1) : those failures are not seen during your tests. Keeping in mind that this phase is super-short (shorter than T3113), don’t you think the BSC will act as a “buffer”, and when the MS is finally in MM state, the BSC will properly route the paging onto the FACCH ?
As long as T3113 is not expired in the MSC, the paging is not considered as failed. Usually this timer is about 3 seconds. That’s much longer than the SMS setup time.
maybe, the MSC retransmits a second paging after the first paging went unanswered. The second occurence should be successfull…
In such case you should see a failure of the first paging occurence, but a success for the paging altogether.