I use t-Mobile in the States with my iPhone 6s. My 5Gb data plan is very much in excess of my usual needs, so t-Mobile "snowballs" the unused data monthly. I have traveled in several European countries and used my data seamlessly, and without extra roaming charges. All texting is also free.
When my phone rings in Europe with a US number, I reply with a standard text (see Phone in Settings) stating that I am unable to take the call...send me text or e-mail. Urgent calls are answered and an agreement to return the call using Wi-Fi at a later time is made. I do this in less than one-minute, so the call costs USD .20. Five such calls run up a USD one dollar tab. So that is not onerous to me.
I visited friends in Belgium in March, walked from Madrid in April, and worked as a volunteer for a month in July-August at the Pilgrim Office in Santiago. My t-Mobile service worked through the Belgium (Proximus) Spanish (Movistar or sometimes Orange) roaming partners seamlessly and flawlessly. It gave me continuous GPS, mapping, translation, text, internet research, hotel booking, and e-mail coverage, to the extent I desired the interruptions...I controlled the usage and incoming traffic.
Using this for the first Camino (in April) since adopting a smart phone convinced me that the comparative weight of the phone and charger were far superior to carrying a old-school guide book. Are you listening Mr.
Brierley?
Besides, veterans like me, know that simply following the arrows will get you where you need to be eventually. Any guide, analog or electronic, is simply an optional benefit. Carrying a mobile phone is primarily for emergency use, and to call ahead to make lodging bookings if one does not use albergues.
When I was in a place with "free" Wi-Fi, I was able to turn off using cellular services for voice calls, and place voice calls over Wi-Fi using Face Time Audio. So, I was able to make routine, scheduled contacts with my wife and elderly parents without problems. Again, this arrangement was FREE.
One day, I even had a two-hour Face Time call with my wife (we are renovating a home in FL and had a lot to discuss). My cost was exactly ZERO! This call used my accumulated, more than 20 Gb of "snowballed" data with t-Mobile
Yup! I am sold. If you travel internationally, t-Mobile is the way to go for US subscribers.
However, I do recommend having a Euro or Spanish SIM card for making voice calls. I accomplish this by having an older, SMS Samsung "flip phone" with an inexpensive voice/text SIM, as SYates recommends above. This phone is my emergency, back-up means of calling 112 for emergencies, or if my smart Phone runs out of charge. I charge the older phone weekly, and it is good to go...all week. It rides in a ziplock bag in a cargo pocket of my pants...so it is ALWAYS with me.
My wife is traveling to India and Nepal at the end of October. I am trying to get her to come onto my t-Mobile plan as a second number, from ATT. She will not have it. .. Happy Wife....Happy Life... So, we are scrambling to try to find something else that is economically viable...using ATT overseas will bankrupt us.
However, I will plan to give her the second, emergency SMS phone with the Euro SIM in it so she can reach out for help if needed. It uses a micro USB cable for charging, so I will replace her Apple Lightning cable with a duo-cable with both Lightning and micro USB tips.
I hope this helps.