I used Verizon in Aruba once and it was a nightmare, but love it in the US. When I needed a new phone, I bought a Moto G, unlocked dual phone. Now when I travel, I get a local pay as you go SIM card.
In the US, I have verizon service and a flip phone.
My extremely inexpensive low-tech way to deal with months spent in Europe annually:
Buy a very inexpensive phone at a phone store wherever we land and load it with minutes as needed. Cost is generally less than $30 for my use.
Use my kindle to access free wifi. Friends and family in the US email me if they need me, I read the email on the kindle, and email or call them back with my European phone.
A few years back I had planned to get a smart phone for international travel, but no one in the verizon store was able/wanted to assist me with figuring it out, so the above is my work around and it works just fine for me.
Instead of using GPS, I look up maps on my kindle. Generally GPS is too high tech for me to figure out.
These days I almost always have the kindle in my handbag because it has all my books on it. It was a few years before I figured out it worked as a computer as well.
Haven’t read all the responses, so sorry if duplicated. We have TMobile. Free texting nearly anywhere in the EU, definitely France, Germany, Prague, Austria. Calls were 20 cents per minute via phone connection. Free calls via WIFI. Most calls were via WIFI (had to turn off cell connection to force the WIFI feature). Occasionally had to make a call ‘on the road’, but these were typically very short, so 20cents a minute was no problem. We bought a sim card AND phone (old-fashioned bar phone) when in the UK, but that was 7 years ago. It was extremely reasonable then, but I’m guessing no need now with the TM plan and smart phones.
Have not yet read the posts, but see France & UK, if you are in the UK first, you should be able to to get a sim card from THREE or other mobile stores with assorted plans that work in both places.