Its also worth haggling with your own mobile network company. I have had a contract phone with Orange for 5 years and recently called their customer service and told them I was thinking of leaving ( ) I negotiated a deal which is half the price and also asked if I could call and sms one number in Turkey at a special rate - they agreed to all my "demands" - yessssss!

When i saw this i had immediately run to the company...
and i was going to buy one... when i asked that if a vodaphone user from abroad will be able to call as if we are another vodaphone user... he said "no"
i dont know maybe he didnt know enough either... but still thinking to buy one