I found different inputs from the different audience. But what I know and believe "when an UE IMSI PLMN does not match with the PLMN being served by MME , is considered as roaming UE".
IMSI = MCC + MNC + MSIN
PLMN = MCC + MNC
If MCC and MNC of IMSI does not match with MCC and MNC of PLMN, then that UE is considered as roaming.
How PGW selection in roaming scenario impacts network performance ?
Does the MME or LTE core network assign the same list of TAI to each user originates from same cell ?
If answer is "no" then what would be all possible methods to manage this task ?
Can someone please share the call flow or network diagram which show how an IMS call establishes between UE and the network ?