Newbie to eSim and dual sim - please help

Hi Louise, see below:

My understanding is that I can either purchase a data only esim or one that also includes a phone number. Is there an advantage to having a European phone number?
Most tourist eSIMs are data only. With a dual SIM phone, you could buy an additional physical SIM when you arrive in Spain, and use that instead. The advantage of having a Spanish number is that you can call hotels, restaurants etc at local rates, and people can call you using a normal phone call. You can't do that with a data-only eSIm UNLESS you sign up for a voice-over-IP service like Skype.

Do Iphone messages only require data usage (in other words they will work regardless of which sim I'm active on)?
iPhone (iMessage) messaging is data to other iPhones, but uses SMS messaging on the phone network to non-iPhones.

If I get signed out of an app that will send me a text to my main number for 2-factor authentication, will I receive that when I'm using the alternate eSim?
Not if it's data only. But you can keep your existing US SIM active in your phone to receive SMS messages, without any additional charge. Just ensure you have roaming with your carrier.

Do platforms such as Facetime and WhatsApp only require data? Could my family rely on these to reach me at any time?
That's correct, data only. If you're solely relying on a data-only eSIM, something like WhatsApp is the best way for family and friends to call you. They only need your phone number, and then they use the WhatsApp app to make either a voice or video call.

When switching to the international data plan, are there any settings I should be aware of to be sure my main cellular does not get activated and charged?
I'm assuming you will:
1. Keep your US SIM active to receive text messages. Make sure you have roaming with your carrier, and that the roaming setting for that SIM is set to 'on' in your phone's setting (worth checking, as it may be set of 'off' if you haven't used roaming before)..
2. Purchase a data-only eSIM for Spain. Follow the instructions to activate, and make sure your phone's setting are adjusted so that data is used via the eSIM.

If you buy a local Spanish physical SIM on arrival, you can ask staff in the store to set it up. The main thing to watch for is to go to your phone's SIM settings and ensure voice, data and SMS are all set to use your new SIM as default. You can keep your US SIM, and it will still work to receive calls and SMS. To avoid roaming bills, you should not answer any incoming calls on your US number.

1. Yes.
2. Yes.
3. No.
4. Yes. Yes.
5. Yes.

A few quick tips - iMessage, WhatsApp etc will work fine between your phones and family since they just need data. Make sure your phone number abroad gets added to your contacts so 2FA texts go through. And definitely switch off cell data for your primary SIM to avoid roaming charges. Have a great trip! :)

My understanding is that I can either purchase a data only esim or one that also includes a phone number. Is there an advantage to having a European phone number?

Hi, Louise. I've used eSIMs with great success (my favorite is Airalo, but there are others). First off, if you want a phone number, that's fine, but I doubt you will need one. You do not need a phone to make restaurants reservations - most restaurants that require reservations accept them online or you could stop by. And for calling home, if you're calling from the hotel, I would suggest using either FaceTime or WhatsApp to make voice calls (or video if you like). I have an iPhone and that's what I do when I want to contact my family at home. if you really want a phone, then yes, you would be given a European phone number.

Do Iphone messages only require data usage (in other words they will work regardless of which sim I'm active on)?

Yes, iphone messages only need data to work.

If I get signed out of an app that will send me a text to my main number for 2-factor authentication, will I receive that when I'm using the alternate eSim?

I would encourage you to try and avoid the 2-factor authentication while you're in Europe. Maybe change the notifications to email instead of SMS. I think it avoids potential problems, and that's what I did.

Do platforms such as Facetime and WhatsApp only require data? Could my family rely on these to reach me at any time?

Yes, I had a data-only eSIM and used FaceTime and WhatsApp to contact my family while in Europe and it works very well. And your family could certainly use those 2 apps to contact you.

There is a wealth of information in the Technology Tips forum, so you may want to look through there. Also keep in mind that most eSIM carriers will give you detailed instructions on how to install and activate the eSIM, so you should not have any problems.

Not yet covered by responses: you must make sure your carrier has unlocked your phone so you can use the eSim in the second sim spot. Each company has a different policy so you will need to confirm.

Thank you - all of the replies are very helpful!

I'm still confused about one aspect. It sounds like from the responses above, if I purchase a data only eSim for Europe, I would turn off cellular data for my primary sim, but set voice and SMS to my primary sim and allow roaming for the primary. Is my understanding correct? Would I then incur roaming charges for incoming calls/texts received?

Also, what are the recommended settings for each sim for Allow Wifi Calling?

Thank you so much.

I used the Airelo app in September in the UK. It lets you select the country you will be traveling in to make sure you get an in-country provider. I bought a $5 esim and easily added more $ during the trip. It worked great but my only mistake was downloading the esim in the US just before the flight left for the UK. Should have waited until I landed at Heathrow and used the airport wifi to download the esim (I had to go through some extra steps to correct my mistake). Once the esim is loaded, you can go to settings-cellular and should see both esims ( your current carrier and a second esim). Turn off cellular data for your personal phone number (usually shown as the primary carrier) and turn on cellular data for the second esim. This allows you to still make and receive phone calls (based on the rates of your current carrier) and all data usage will flow through the second esim (iPhone text messages, WhatsApp, FaceTime, internet browser, etc.). I suggest you visit the Airelo web site to get a better understanding how it works. Their app also tracks usage so you can see when you need to add more data.

To add to Frank's answer (and your question about charges), you won't pay to receive incoming SMS messages while roaming, but you will pay to make or receive calls, or send SMSs. I normally just don't answer inbound calls on the telephone network - fortunately coming from Singapore, almost all calls for personal and work are via WhatsApp, so that makes it easier.