what type of RNTI used for scrambling ETWS paging message and UE specific paging message?

Question

PagingUE-Identity ::= CHOICE {
s-TMSI S-TMSI,
imsi IMSI,
...
}

As pagingUE identity should contain any one of these in paging message so how MME decides which one to send, though for security purpose MME prefers t-o send send S-TMSI but in which scenarion MME wil use imsi as paging ue identity.

Answer 1

all paging message will be identified by PRNTI (65534)which is common for all paging message.

Answer 2

It's P-RNTI
Value of P-RNTI = 0XFFFE