I saw a poster lasgt night at what seems to be an amazing mobile offer so I thought I'd pass it on.
I believe the poster for Mucho Moblie says that up until the end of 2011 your can use their prepay service to call many overseas countries for free.
The only drawbacks I could see were that it's only the first 15 minutes are free so if you go over 16 mins you get charged (I guess quite a high rate) and of all the countries listed it did not include the USA.
I didn't have time to read the small print so there might be limitations to the number of calls you can make per day.
Anyhow it soinds like the introductory offer is pretty good. Not sure how much the SIM cards are but you normally get some free minutes included when you sign up for pre-pay networks.
www.muchomobile.ch
Cheers,
HB2