US cellular

By using Whatsapp or Signal (or other) for calls, the free wifi that you will have almost everywhere could not be enough?
If you are connected by Wifi, this allows you to use your email and also to use the airline applications with which you receive information and notifications and can check in most of the time.

Thank you JoLui. I knew I could use WIFI but have never used either App. I will look into both.

Cathy, see if you can setup Google Voice before you leave for France. This will allow you to make and receive free voice calls with the Google Voice app, even to landlines. So you could call bank or airline if need be - be on hold for an hour and it's free. But you need WiFi or mobile data. If you don't have actual mobile service in France, you'll need to stick to WiFi. Google gives you another US phone number that people can call/text and you will get calls and texts in the Google Voice app. But it won't work with your original US Cellular phone number.

See if US Cellular supports the "WiFi calling" feature and what it costs if anything. If they do, you can use your phone FREE while on WiFi, for both making and receiving calls and texts.