It doesn't have to be a smartphone to hold more than one SIM. I have two simple $25 phones I bought on Amazon - one holds two SIMs, the other three. They have every feature anyone might need on vacation (camera, video, music, email, etc.).

But yes, whenever you change a SIM card, you're back to the original number and data storage on that SIM.

Again, thanks so much!

I'd buy 4 "3" Pay-as-you-go http://www.three.co.uk/Store/Pay_As_You_Go_Price_Plans SIM delivered for free to your first UK hotel

You just load as much money on it as you want (from a credit or dent card) and it will teach the kids the benefit of using free wifi.

works out as 3p a minute voice, 2p a text and 1p a Mbyte you also get some free MB for the first month of joining

In the UK, in any town or on the train I struggle to use any money on this card as there are so many free wifi points about. In Germany it will prove harder but this account is set up to have similar costs there.

We had a Verizon international plan for one phone a few months ago and it wasn't expensive, about $40. Your kids do not need to use their phones in Europe; they can use them on WiFi.

I agree, most teens are addicted to their phones, but the main reason we want them to have phones is to check in with us so they can have some independence while we're there. I don't want to turn them loose in foreign cities with no way to reach us if they get into trouble or are running late for check-in times.

Agreed, they can stay in touch with friends at night in the hostel with wifi access. That's not the primary need for phone access.

If you don't need to talk, then you can use WhatsApp. We do it all the time, even with T-Mobile.