Sim card

You can't order Italian SIMs ahead of time - you must buy them in country and activate them by showing your passport.

You can buy SIMs from other countries like the UK and the Netherlands ahead of time because those countries don't require registering your passport in country to activate - and then you can roam in other EU countries like Italy. (Most roaming fees have been abolished in the EU.) But if you need to make local Italian calls while you are there, a UK or Dutch SIM may have limited calling ability to other EU countries, so you might be better off with an Italian SIM.

I had good luck with a Dutch Vodafone SIM last year - bought it on eBay, used it in Slovenia, Italy, and France. Never even visited the Netherlands. But I needed only data and didn't care about local calls.

a UK or Dutch SIM may have limited calling ability to other EU countries, so you might be better off with an Italian SIM.

Current rules require roaming free-of-additional-charge throughout the EU. We bought SIMs in London where we landed for our 8-week trip and they provided excellent service in The Netherlands, France, Germany, and Italy as well.

We always buy at port-of-entry and in Milano, I would buy from TIM if possible. If you will be more than 30 days, buy an additional voucher for topping up unless you will be near a TIM store again at renewal point. Ask if you need more detail on this nuance.

Depending how long you are staying you may also want to compare with renting a wifi hotspot.
Since one hotspot can power multiple devices and connects to more than 1 cell companies service, that is my preferred option.
I think roughly the cost is comparable if staying for 1 week ; longer stays and the cost of the hotspot is higher but is still my preference.
I have used a couple of different services.

I've been doing some extensive research lately because I'll be going to Italy at the first of June. I've used a company called Mobal before and have one of their talk/text only phones with a UK number. Will be taking that one plus I'll be getting one of their SIM cards for my personal phone. It's a really good deal and you can get it shipped to you before you go. The SIM is active from the time you tell them to activate it for a total of 1 month. You can keep the SIM card and reactivate it the next time you travel. Reasonable rates plus 1G free data. Give them a try at Mobal.com.

Laurel:

Current rules require roaming free-of-additional-charge throughout the EU. We bought SIMs in London where we landed for our 8-week trip and they provided excellent service in The Netherlands, France, Germany, and Italy as well.

Right, but the rules don't apply to making calls to other EU countries for the same rate as calling your home country. "Roam-like-at-home" means the phone costs you the same to use while in another EU country as it costs to use at home. It doesn't mean it must cost the same to call, say the UK if you have a UK SIM as it costs to call French numbers. But it most cost the same whether you are home or in another EU country.

That's what I was getting at. My Dutch Vodafone SIM included only a few calling minutes at all in the "You" bundles they were offering, and they were good only for calling Dutch numbers. Calling non-Dutch numbers was not included in the bundle and would incur a per-minute fee. It would have been more expensive for me to call phones in Slovenia, Italy, or France (where I was traveling) with the SIM than using Skype for example. But every mobile plan is different.

My point was: don't buy the Dutch Vodafone SIM ahead of time if you plan to make calls to Italy - just wait and buy an Italian SIM when you get there. Or find some other SIM that allows calling various EU countries at an affordable rate. If all you need is data (all I needed) then no worries - roaming data costs the same as "home" data.

Caution: Check with your cell phone company. I did a bunch of research and was all ready to get an international plan from my local T-Mobile store. Then I called my cell phone provider and they said their phones do not allow international plans.

They do allow SIM cards, but -- as I'm sure you know -- with a SIM card you have a different phone number until you get home and swap in your regular US SIM card. I didn't want to be traveling with a different phone number because I'd made all my hotel bookings with my regular US cell phone number as my contact number. In case of some problem, they wouldn't be able to call me if they didn't know my in-country SIM number.

Caution: Check with your cell phone company. I did a bunch of research and was all ready to get an international plan from my local T-Mobile store. Then I called my cell phone provider and they said their phones do not allow international plans.

I'm not sure what you mean. If you have a T-Mobile US post-paid plan (what most T-Mobile customers have, not pre-paid), all of their recent plans of the last few years offer free international roaming data, free texting, and 20 cents/minute calls. If you have a really old T-Mobile plan you are hanging on to, it probably doesn't.

If you mean, you were planning to switch to T-Mobile just for the time you are going overseas? You can do that - I have - but it might not be cost-effective anymore. You probably need to buy a SIM for $25 beyond plus $75 for a month of service (maybe discounts for auto-pay and low data usage). It's much cheaper just to buy an international SIM.

They do allow SIM cards, but -- as I'm sure you know -- with a SIM card you have a different phone number until you get home and swap in your regular US SIM card. I didn't want to be traveling with a different phone number because I'd made all my hotel bookings with my regular US cell phone number as my contact number. In case of some problem, they wouldn't be able to call me if they didn't know my in-country SIM number.

That's why I use my Google Voice number as my regular number at home as well as when I travel. Then I can use Google Hangouts overseas and still receive calls and texts for free while traveling. You can port an existing number to Google Voice for $20 one-time then use it in conjunction with Sprint, T-Mobile, Verizon- AT&T, etc. and do what I do. (I have no idea what my current Sprint mobile number is - I have never given it to anyone, I give them my Google number instead, and it forwards to my Sprint phone.) You can also keep your existing phone service as it is and still get a Google number for free, but it's a new phone number. You could give that to hotels etc. while traveling, and they can call you while traveling - just set Google Hangouts to receive incoming phone calls.

Because I bought the Dutch Vodafone SIM (plan to use it again in the future - it stays active for a year from last time you added credit), I still have a Dutch phone number, and I can give that to European hotels and apartment owners. I can receive free incoming calls on that number, as with most European SIMs. They would probably prefer to have an EU contact number for me anyway instead of a US number, which is probably expensive for them to call.

To Andrew H: Sorry if my comment caused confusion. Yes, I was "planning to switch to T-Mobile just for the time you are going overseas." My cell phone company informed me that their phones will not accommodate this. I have to call my company and have my phone unlocked before I can use it overseas, whether I buy a foreign SIM card or simply continue using the phone in Europe.

You'll probably ask, what kind of cockamamie cell phone company is that? So, here's the name: It is Credo Mobile. The phone worked just fine with my regular number overseas, it just cost a little more.

Yes, I was "planning to switch to T-Mobile just for the time you are going overseas." My cell phone company informed me that their phones will not accommodate this. I have to call my company and have my phone unlocked before I can use it overseas, whether I buy a foreign SIM card or simply continue using the phone in Europe.

You'll probably ask, what kind of cockamamie cell phone company is that? So, here's the name: It is Credo Mobile. The phone worked just fine with my regular number overseas, it just cost a little more.

Yeah, I'm familiar with Credo. If your phone is paid off, they will unlock it for you - but not if you are still paying it off:

https://help.whistleout.com/hc/en-us/articles/115013305648-How-do-I-unlock-my-CREDO-mobile-phone-

Credo doesn't really make sense to me. I know why people use them, but I'd rather pay a lot less for my mobile service and just donate the savings directly to my favorite charities. You can always buy an unlocked phone outright and use it on any carrier you wish (including Credo) and not be stuck with them in a contract.

Just to clarify about Credo and unlocking. I have used it both ways overseas: on one trip with a local SIM card -- actually two different SIM cards in two different countries -- and on another trip having it unlocked for overseas use but keeping my regular phone number and SIM. Credo's help desk was fine with unlocking it either way.

But when I told Credo I was going to my local T-Mobil store to buy an international (multi-country) SIM card so that I could have the SIM before leaving home (thus knowing my overseas phone number ahead of time) and use it in more than one country, they said that wasn't possible with my phone.

This was definitely not related to any question of the phone not being paid off. I bought the phone outright when I first got it, and had already had it unlocked for an overseas trip about a year before this happened, so their telling me I couldn't use a multi-country SIM didn't have anything to do with my phone not being paid off.

You can't order Italian SIMs ahead of time - you must buy them in country and activate them by showing your passport.

TIM for Visitors Italian SIM?

https://community.ricksteves.com/travel-forum/tech-tips/tim-for-visitors-italian-sim

Yes, I was "planning to switch to T-Mobile just for the time you are going overseas."

A great deal if you qualify:

https://www.t-mobile.com/offers/t-mobile-one-unlimited-55

Consider an additional $10/line/month for the One Plus Plan, which gives you "2x the data speed abroad". Free international roaming is 2G only, which can be unbearable.

https://www.t-mobile.com/cell-phone-plans?icid=WMM_TM_Q117TMO1PL_2SADAX76BBT7513