Crooks are apparently turning to Skype in increasing numbers, attracted not just by the free calls and anonymity but also the company’s refusal to share its encryption keys with police and security agencies.

Italian customs and tax police are the most recent to complain, expressing frustration over the rising number of criminals using Skype to frustrate wire-tapping and mobile phone interception efforts. The BBC reports officers in Milan as overhearing a suspected cocaine trafficker instructing an accomplice to switch to Skype to get the logistical details of a two kilogram shipment.

German police have also been highly critical of Skype’s refusal to share its encryption keys with security forces. Even the country’s chief of police has complained: Joerg Ziercke, president of Germany's Federal Police Office (BKA), has admitted Skype’s encryption has his force stumped.

“We can't decipher it. The encryption with Skype telephone software creates grave difficulties for us," Ziercke told reporters at a gathering of security and law enforcement.

However he came short of asking Skype to hand over its encryption keys, saying “there are no discussions with Skype. I don't think that would help.”

He’s probably right. Skype is only one of many providers of free VoIP, albeit the most popular. If it were to unlock its traffic for police investigations and compromise its proffered anonymity, no doubt others would quickly fill the gap.

Compliance on behalf of Skype would also open the highly-sensitive can of worms over which agencies to allow access to, particularly in countries like China where police more intimately involve themselves in the online affairs of the citizenry. Indeed, Skype already cooperates with Chinese authorities through the version provided by its local partner, TOM Online Inc.

But if businesses are using VoIP to cut down costs, is it at all surprising to see criminals doing the same?