Cell phones in Europe

https://www.ricksteves.com/travel-tips/phones-tech

It depends on your phone and your carrier. There are some carriers that provide a free or low cost international plan and others that make you pay through the nose. If yours is the former, it's usually easiest just to keep that plan while you're traveling. If yours is the latter, you may want to pay the extra fees to your carrier in the name of convenience. I choose not to do that (I have Verizon, which has an expensive int'l plan) but others like the convenience.

The other options are to buy a physical SIM card, which allow you not only a data plan but also the ability to make phone calls in Europe. The disadvantage is that you cannot use your regular phone number - instead you will be given one from the country your plan is with.

You can also get an eSIM plan, which is done digitally (no having to transfer physical SIM cards). Most eSIM plans are fairly cheap - the only disadvantages are that your phone must be unlocked and you usually (with some exceptions) do not get a phone number. Most people who use eSIMs (myself included) are fine with that - we get around it by using apps like WhatsApp, FaceTime, Google Voice or Skype among others to make calls, which you do by using wifi, which is abundant in Europe.

There are a lot of posts dealing with physical SIMs and eSIMs on the Technology Tips forum, but if you want to give us more information about your phone and carrier, there are people here who will help.

Who is your current mobile provider at home? if you have AT&T, Verizon, or T-Mobile, I'd probably just use their international roaming plan (might be free with T-Mobile). Otherwise, I'd probably buy a SIM card when you get there, yes. Just make sure your phone is unlocked and will work in Europe (probably will).

Your phone will work on WiFi anyway (for email, web browsing, etc.) whether you have a SIM card in it or not. And if your carrier supports "WiFi Calling" you might be able to use it while on WiFi for calls and texts on your US phone number. Buying a SIM card means you have a European phone number temporarily until you start using your US SIM again.

Install the Google Voice app before you leave for Europe, so you can make free calls home to US numbers, even landlines. Google gives you a new US phone number you can use for calls and texts in the Google Voice app - even if you just use WiFi.

We just get T Mobil's international service, and our phone works the same there as it does "back home." We kept getting phone calls at 3:00 from a 4 year old granddaughter that didn't understand time changes.

When we get home, we discontinue the service.

T Mobil is owned by the German telephone company.

I've tried to use a foreign SIM card and had a problem. The customer service people only spoke Italian.

We are on Verizon, and we use their TravelPass plan. It's $10/day to access whatever your plan is (I would guess most people have some version of unlimited everything). BUT, you only get charged if you actually use it. We find it works well, but we also have not needed cell service daily while on trips. Verizon also has an international plan that is, I think, $100 for a month, but it limits your data.

Don't know about any US plans, but for us, in Canada, I wouldn't take a chance on using my own provider, for fear of incurring exorbitant fees upon my return! I get a local SIM. Remember, you don't need a data plan to use the GPS in your phone, and you can make calls through WhatsApp/Messenger and others, using data from hotels and the like.

I have ATT. I didn’t want to mess around and try to figure it out. For $15 a day for 2 lines it was worth being able to use our phones as if we were here in the States.

That depends on the options provided by whatever cell network you subscribe to. These days I normally just use the Roam Like Home plan offered by my cell network. That provides the same voice, text and data features that I have at home, so no difference at all in how I use the phone in Europe. It's a bit expensive but it sure does work well.