Amazon.com: UK Vodafone SIM Card Fast 4G Free Roaming in Europe:
1. Insert SIM into your phone, make sure you enable data roaming
2. Wait for the signal, your phone will prompt you to select the SIM APN, make sure you select Vodafone PAYG Wap, as this is the correct APN for your internet settings
3.Text INTERNATIONAL to 2345 to enjoy cheap Int'l calls, e.g. 2p per min to the USA, wait for confirmation text from Vodafone before you make any calls
4.That’s it you are all set to go!