LTE: How does MME make out that a user belong to the home network or roaming one ?

Question

How PGW selection in roaming scenario impacts network performance ?

Answer 1

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".

Comments

Even I have the same understanding !

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Does the MME serve an UE who's IMSI PLMN not matching with the MME PLMN ?

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As my understanding Roaming decision will be taken with help of HLR and VLR . If PLMN is part of equivalent PLMN list then MME serves.

Answer 2

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.