http://www.bbc.co.uk/news/technology-12094227
QuoteMobile calls and texts made on any GSM network can be eavesdropped upon using four cheap phones and open source software, say security researchers.
Karsten Nohl and Sylvain Munaut demonstrated their eavesdropping toolkit at the Chaos Computer Club Congress (CCC) in Berlin.
The work builds on earlier research that has found holes in many parts of the most widely used mobile technology.
The pair spent a year putting together the parts of the eavesdropping toolkit.
"Now there's a path from your telephone number to me finding you and listening to your calls," Mr Nohl told BBC News. "The whole way."
He said many of the pieces in the eavesdropping toolkit already existed thanks to work by other security researchers but there was one part the pair had to create themselves.
"The one piece that completed the chain was the ability to record data off the air," he said......... (more)
I don't suppose we're surprised, though a lot of people will be.
I'll tell the wife might save a bit of money. >:D
Its why they had to strengthen the encryption for 3G.
Its also possible to set up a bogus GSM network to steal authentication data which is why 3G has mutual authentication whereby the phone and SIM authenticate themselves to the network but the network has to authenticate itself to the SIM.