iMessage and Facetime number expiring soon.

I’m overseas right now so I am using a different SIM card. I am from the US and I return in a week. I just received a Settings notification saying my iMessage and Facetime number was expiring in 5 days and I need to reinsert it to continue using the number with iMessage and Facetime.

What happens if I don’t reinsert it until i return to the US in a week? will that mess something up and I cannot text or call my friend to pick me up?

Or should i try to play it safe and just reinsert it while i’m overseas? even though there is no cell tower that will be compatible, will it satisfy the notification because the SIM card is in the iPhone again? and then i will take it back out for the remainder of the trip?