Do you use your mobile phone such as iPhone when traveling to connect to the net so can this wiki help:
Pay as you go sim with data Wiki
You can find telephone operators offering prepaid SIM-kort/kontantkort that makes it possible to surf the web with iPhon, Android phone, etc. You do not need to take out a subscription to use your iPhone or use your iPhone as a modem with the SIM card.
Other sites with information about prepaid / prepaid iPhone / smartphone .
