A drop means the call is stopped. Then, a reselection can occur, but it’s not considered as a HO.
So a interPLMN HO is just a standard HO, but towards a neighbour that belongs to a different PLMN. The triggering conditions are the same as for intra-plmn HO.
The activation steps are:
1/ PLMN definition in the OMC-R
2/ Adjacency links for handovers
to define handover adjacency links towards an external cell belonging to a foreign PLMN.
NCC_PERMITTED–> must be tuned to accept the new NCC !!
3/ Adjacency links for cell reselection
4/ CGI_REQD shall be set to “CGI used”
In the NSS, i don’t know what shall be done.