I think this thread has pretty much run its course, but here's my summary response:
1) If you have Visible, you won't have international calling with them.
2) If you have Visible, your phone is unlocked, so that means you can use a SIM card or an eSIM.
3) Before deciding between a SIM or eSIM, install WhatsApp on your iPhone and practice calling friends and family on that app before departing the US. It will work off of both cellular or WiFi service.
4) You can buy a SIM card at the Madrid airport.
The advantage to that is that you stroll into an airport cell phone store and ask the person to literally insert the new SIM card for you. Just make sure you watch so you can put in your old Visible SIM card when you land back in the US.
5) Alternatively, you can download an eSIM before leaving the US. In my research,,
Airalo is a decent brand. T
he advantage to this is that you can download the eSIM at home and have phone service as soon as you touch down in Madrid.
6) Both options are crazy cheap compared to using an international calling plan. You can choose plans that vary in duration and GB of data.
7) Make phone calls and text via WhatsApp. It will work off cell data or WiFi, so you'll always be in contact with friends and family in the US.
8) When you get home, switch back to you usual SIM or eSIM.
Hope this helps!