Joan, I hope its OK if I ask a slightly different question as everyone here is so helpful.

Can anyone recommend a phone or service we could cheaply use that we could use occasionally to make calls with within Europe but also use for its GPS? We plan to rent a car for a couple of weeks but have also found GPS helpful while walking about.

Any modern smartphone (Android, iPhone, Windows phone, etc.) will have GPS. The GPS function will actually work WITHOUT having local cell service, but the maps may not. If the phone is unlocked, you can buy a local SIM card for it and use it as a GPS with maps while you drive.

You may be able to use the phone only on WiFi and pre-download maps on WiFi before you drive - the GPS, again, should work without any local SIM card. If you have a local SIM and local service, you can just use the built-in Map service (Google Maps for Android) for a GPS with maps.

What kind of phone and service do you have now?

Cheap Android phones may not have all frequencies needed to work at the higher speeds (3G and higher) in Europe. I think any iPhone or expensive Android will work at 3G or higher though. I already know my new (cheap) Android won't work at 3G in Europe so I may buy another phone before my next trip to get the faster speeds. (You want 3G or faster so that maps can be downloaded more quickly on the fly; 2G speeds can be a little slow.)

Thanks for all your info Andrew. We have iPhones and At&T service.

I don't know much about iPhones, but I would find out if they are unlocked (check with AT&T). Then I'd buy a SIM card when you get to Europe. You will need to get a "nano" SIM card for an iPhone, though, I think. It may also be possible to get a SIM card that is data-only (cheaper - what someone might get for an iPad).

You can try out your iPhones now for navigation before you travel. It will work the same in Europe as long as you have a SIM card with data.

You can use the Google Hangouts option for free calls home to the US if you want (free on WiFi, uses data if you don't have WiFi) - and you can set that all up and try it before you get to Europe, following my instructions above.

For travelers the ability to do cheap international calls is crucial. I advice to use voip calling apps, they offer cheapest rates. I am using YunGO for several months and like it. With it I can call to Germany and France at 3 cent per minute. I think it is a cheapest possible rate, I couldn't able find cheaper. And what is good it works both for my Samsung Galsxy 4 and iPhone 5.