using a roaming prepaid sim card has on this trip been absolutely frustrating. I would still like to find a reasonable solution for using a mobile phone in EU without having to pay an arm and a leg, or having to swap phone cards every time I enter a new country.
WorldSim: had promise but it turns out that my sim got messed up. In fact the number assigned to the sim changed twice so far, so that now I can't seem to top it up.
Telestial: this is the service I had the first time and it has so far worked the best. I only tried the worldsim because it was available at the airport store when I landed in Amsterdam
You will want to have an unlocked GSM tri or quad band phone to use one of these cell phone SIM cards.
There are certainly other providers out there which I have not tried yet. But I need to find one solution, soon.