no overall limit of paging requests at BSC level
It seems we don't have any maximum queue depth for paging requests from the MSC. I've created a TTCN3 test that sends 100 new paging requests per second, and I can see the per-BTS paging queue grow to > 4000 entries, associated with the BSC spending all the CPU cycles it can get in
Paging: 4004 pending requests, 16 free slots
I think there shold be some upper limit for the per-BTS paging queue at the BSC.