Rebtel - connecting people by local numbers

Rebtel permits two people in different countries to dial local numbers to connect each other. Here's the deal:

1. You enter numbers into your Rebtel address book.
   
2. Next to each entry, there's a local telephone number (local to you, the caller).
   
3. You dial that number and your friend's phone rings (even if it is one the other side of the world.)
   
4. They answer. (The call appears to come from a local number to them.)
   
5. They hang up (you stay on the line).
   
6. They call you back on their local number.
   
7. You can talk for the cost of a local call.

The whole concept is very nice indeed. In calling the UK, it failed at step 5 - the recipient couldn't hang up and call me back - I was still on the line. 

If they called me in US and I hung up and called back, then it worked fine.

I'm sure Rebtel will have other innovations to follow. (See also Jajah)