How do I use a local SIM card when I travel to Italy?

I’m traveling to Italy next month. My current phone is an iPhone 13 Pro Max but I have an extra (old) iPhone 12 Pro Max that I was looking to use for the international travel.

1. How do local sims work? Does my phone then work as if I’m still in the U.S?

2. Does it matter that I would use a local sim in the extra iPhone while my current iPhone stays “active” in the States?

Re: How do I use a local SIM card when I travel to Italy?
Customer Service Rep

Hello, Cedardell, I hope you have a great trip to Italy! If you would like to use a local SIM while traveling, that is certainly an option. In that case, you will be paying local service rates while traveling and you will have a local number. Can you please clarify your question about your phone working as if you're in the US? If you are using a local SIM in another phone, there would be no need to make changes to your iPhone 13. Your US number will remain on that number, though if you were to use service on that number while traveling there will be additional charges. Does this help answer your question?