With the treatment from skype & three UK, I don't like to be fair because they haven't been honest with customers. However I still think its worth a mention that many of the phones offered by three particularly the older models which used the java skype didn't use proper voip.
It would use partial data connection to communicate who your trying call & the 3g voice network handles the call while forwarding it. If the past you could have hidden & exited skype on your handset (not anymore though) what happened was the skype call would be received by three's data network & forward the call to your phone number while three handles and accepts the data to voice network.
For those screaming out for skype, I suggest your all check out Fring to see if it works on your phones. It has been a useful alternative.
Honestly, I think skype have been lazy to do the work, companies like fring were offering similar & even allowed skype customers to use their software but some issue between them, Personally I think skype was scared of the competition & stopped it.
