thanks for pointing me toward Maxroam and Piranha - lots of innovation going on!
by coincidence, this just appeared on the Truphone blog, perhaps signalling something forthcoming:
Final Countdown for high roaming charges in Europe - The Tru Blog
Truphone does well with very low rates for calls and data in the US, UK, and Australia, and decent rates for short term roaming in rest of Europe. Also very easy to add a UK number for $8 for a month when I visit. But Truphone seems to have been asleep for 2 years while other companies are busy innovating.
I like the way Piranha integrates VOIP, I'd try it just to see how that works. But don't like callback when roaming, (wife wants to keep things simple!)
Also, have to watch the data costs, as costs vary a lot by local provider, and it seems they work with multiple ones in each country.
Interesting that Truphone is officially US-based, originally appeared to be a UK outfit.