Buying a sim card in Italy

The three main operators (Tim, Vodafone, Wind) have shops pretty much everywhere, as well as in/near the airport. You can buy a prepaid sim easily, don't worry, Italy is a very touristic country. You might need to sign some papers when buying the sim but that's all. Just make sure it works in your phone, and that your phone also works with the network frequencies in the country.

More info here :http://www.prepaidgsm.net/en/italy.php

I did buy an Italian prepaid SIM in 2013 and do not recall that I was asked to provide a codice fiscale (I didn't even know at that time what it was and certainly did not have one assigned by the authorities). The process was smooth given that I knew beforehand the option I wanted and only basic Italian or English was involved. A passport / official ID was necessary.

If they do want to have your codice fiscale tell them that you don't have one and give them the choice to calculate it for you (there exist online tools linked to in the others answers), fill it with voids (like in the US you would make your SSN all 9s or 0s) or try at another store.

Codice fiscale is only for people that live in Italy and is not mention for the one that just visit Italy. It is similar as for Social Security code for USA any way you can calculate your Codice fiscale onlie http://www.codicefiscale.com/ provide all the information to the bottom one comune di nascita put the state you were born.

In my experience, the best solution is to buy a Lebara or Lyca Mobile sim card. You can find them almost anywhere, they have decent websites and you can use them in a pay-as-you-go way. Usually big operators like TIM offer services designed for long-term users.

To buy a new SIM, you just need a document with pic.

You can't create or improvise your own Italian fiscal code, you can't make it up, it's a registered code only available for Italian residents, you will need residency to have one. I don't know why in Italy it is required for a simple pay as you go simcard but that's how it is, either you find someone who can buy it then forward it to you (something like this https://www.sourcingitaly.com) of you can buy one on ebay or similar websites, once you have it to top it up it's quite a simple process if you choose one of the main mobile operators, most a ccept PayPal so you can top them up wherever you are, it is usually advisable to top it up every 12 months in order to keep it alive.