How eNB get know about reason for paging

Question

in LTE paging can be happen if
1) upon initiating mt packet switch data
2)csfb
3) change of system info.
4) presence of CMAS/ETWS
how eNB knows for which purpose it has to send paging to ue?

Answer 1

CMAS/ETWS and SI based paging are enb initiated paging messages for which separate indication flags like update of siValueTag and enable of etws/cmas indications in paging message. For idle UEs, the paging is network based coming from mme with necessary information like tmsi etc.