It doesn’t matter how many times the networks tell you “roaming is getting cheaper” it’s still a crazy amount of money and my advice has to remain the same. Don’t use your phone abroad unless it’s an emergency, otherwise you WILL be paying up to 1 per minute – sometimes even more.
Here’s a bill for just three calls which ended up costing me nearly 21. I did actually buy a AT&T “Go Phone” card in the US but had to use my normal UK mobile when the battery went flat. This is the result – 21 for about 17 minutes on the phone.