How do you use Facetime?
I've had an iPhone 4 for a couple months now, but not yet used facetime. It comes up as a button when I make a call, but nothing happens when I press it. SO I really have 2 queries here:
1. Can you only use it iPhone 4 to iPhone 4 - or do older iPhones work too (tried it to my sister's iPhone 3g, didn't work)?
2. Can you use it anywhere, on the wifi or the data plan?