What I'd do, is just get a pay as you go phone that has international service in the country/countries you'll be in across the pond.
You will pay much higher rates internationally with US carriers, but it's worth it compared to being stranded somewhere. There's also no contract that I'm aware of, besides being on the hook to pay for what you use. You probably also have to pay the full, unsubsidized cost of a phone to use.
I know Verizon offers some kind of international service and pay as you go phones. Whether the two can be combined might be something to ask about.
If you already have cell phones, you should just check with your carrier about using it abroad. It'll likely just cost extra for every call you make or text you send, but it would simplify things a great deal. Also, if you're making limited calls, it shouldn't be a big deal.
We'll be in Europe for 3 weeks and are considering a
cell phone for emergency calls and possible limited
use(texting) for our 17 year daughter who will be traveling
I've searched on Fodors Europe forum where there is a fair
amount of info - wondering if any of you have experience
with Mobal World phone: www.mobalrental.com
I was also going to try to call Verizon today
as I understand you can rent an international phone from them.