Traveling to Spain and need a phone plan

I was in Spain earlier in the year, and just used my normal phone plan with roaming, which includes calls as well as data.

If that's not an option, go for a travel eSIM. As you have correctly noticed, they are normally data-only, but if all you need it for is to be able to message or call your son if you're separated, this will be fine- just used WhatsApp (or a similar messaging app). Presumably he's not going to need to call a landlines phone.

FYI, in case of an emergency, he will still be able to call the emergency services (which is 112) even if he doesn't have voice calls on his plan.

OP, your initial post is a bit confusing, at least to me....

You say you don't want your son having a working phone, but you want to call him
if you get separated while traveling. And you say you want it to work in Spain and
the US, but it is not clear to me why you would need it to work in the US if you don't
want him to have a working phone when you're all at home.

So, your son is with you, and the phone is just for abnormal situation while you are
all on the trip? But you still need a new/different phone, right? And is there some
reason you are leaning towards prepaid?

You could consider buying a cheap burner phone in Spain with an eSim that has
both voice and data. Nice thing is that the eSim could be put into a different phone
at a later time. Or buy a cheap used phone that supports eSim (or single Sim may
suffice) here in the US before you travel. Look at Airalo or there are tons of eSim
providers.

I am not 100% sure about this, but prepaid plans you would get from a US carrier
probably don't support international calling, and data roaming charges could be
exorbitant.

Welcome to the forum, tygibs.59501 It may go without saying, but you need to make sure you have an international plan on your TMobile account for both you and your wife. Otherwise you can't call or text each other or your son without an exorbitant fee. Read details carefully, they do have different kinds of plans (some say "international" but they're actually just to call overseas from the US, not make calls while you're overseas). Some have unlimited texts but not all have unlimited calls. I agree that most if not all prepaid plans purchased here in the US will not have good, or any, international coverage. If you get a burner phone in Spain for your son, he'll have a Spanish phone number (thus the need to confirm your own phone coverage).

I may not understand what you need, but here's a possible option:

Go on Ebay and buy an Ultramobile Sim card for $13. Only for sale on Ebay.
Make an Ultramobile account, activate the sim and give them $10.

Go on Ebay if needed, and get another older cheap UNLOCKED phone
Put the UM sim in it.

The Ultramobile plan costs $3 /month (really). It gives you 100 texts, 100 minutes, and 100 mb. data per month, in the U.S. Internationally, each minute of call costs $1.49, each text is $ .50 sending, $ .10 receiving.
If you think he might use up the extra $ 7.00 in making calls or texts, then maybe give UM more than $10 to start. If you wish to, you could keep the account active for 12 x $3 = $36/year.

I have one of these sims in an old phone I carry as a backup. Works fine in Europe. I also have one in a Moxee box at home, so we can keep our old home landline working for $36/year.

My wife and I have an old Tmobile Magenta plan for $70/month (2 lines) which gives us international roaming which works very well for us.

There maybe an easier solutions if the concern is strictly about separation. In the old days before cell phones when we traveled with our two sons, we would give each of them a hotel business card and wrap about 20, 25 in local currency around the card. Now the drill was. --- if you get separated try to return to the last place we were together and wait about 30 minutes. If that fails, find a taxi, given them the hotel card and you money to pay. The system was never tested so I don't know if it would work or not. But that was the plan.

Thank you for all your comments. I am just looking for a prepaid plan that will last the month of June. I would like it to work in the US so that I’m not wasting money for a months plan that only works in Spain. I’ll look into your suggestions! Again thank you!

I am just looking for a prepaid plan that will last the month of
June. I would like it to work in the US so that I’m not wasting money
for a months plan that only works in Spain.

I'm not sure such a thing exists, but if you find it, please do come back and let us know what worked out for you.

OP, even after your additional posts (btw, thanks for those, a lot of people post
questions and never come back or acknowledge the replies), I am still a bit
confused.

1) Do you need to acquire a new phone for this prepaid plan you are looking for?
Unless you have an old phone lying around, I would assume the answer is yes.

2) Why do you require a prepaid plan for a month? As noted, if you find something
that meets your criteria, people here would love to know about it. But the cost
of a Sim or eSim that provides decent amount of voice minutes and data (and
can be purchased with an eye to how long it works before it expires) is pretty
inexpensive. Yes, it's for Spain, but who cares?

If you need a phone no matter what (for prepaid or eSim), a eSim for $16 USD is
not really a big expense in the bigger picture. You need to research prepaid
plans carefully given your requirements; I suspect the hidden costs would be
an issue, or you'd find that there's some fine print that renders your plan ineffective
for your needs.

Example: Spain voice and data eSims

We currently have an unlocked phone for my son that he uses on WiFi. But we are going to Spain for 2 weeks and want him to be able to contact us if he goes with family. Was hoping for an American prepaid so he has a normal phone. My wife and I have T-Mobile and have international coverage. Just wanted to see what everyone else has used and what worked best.