The European Union is considering changing the law so VoIP conversations using services such as Skype can be tapped during law enforcement investigations.
Italian police warned this week that much of the country's crime is organised by VoIP service rather than traditional telephone conversations as it's almost impossible to get a court order to tap a suspect's VoIP service.
The European investigation could also help US law enforcement authorities gain access to internet calls. The National Security Agency (NSA) is understood to believe that suspected terrorists use Skype to circumvent detection.
Eurojust, a European Union agency responsible for coordinating judicial investigations across different jurisdictions, announced an investigation involving all 27 countries of the European Union.
"We will bring investigators from all 27 member states together to find a common approach to this problem," said Joannes Thuy, a spokesman for Eurojust.
The purpose of Eurojust's co-ordination role is to overcome "the technical and judicial obstacles to the interception of internet telephony systems", Eurojust said.
The main obstacles are the differing approaches to data protection in the various EU member states. The investigation is being headed by Eurojust's Italian representative, Carmen Manfredda.
While telecommunications companies are obliged to comply with court orders to monitor calls on land lines and mobile phones, "Skype refuses to cooperate with the authorities", Thuy said.
In addition to the issue of cooperation, there are technical obstacles to tapping Skype calls. The way calls are set up and carried between computers is proprietary, and the encryption system used is strong. It could be possible to monitor the call on the originating or receiving computer using a specially written program, or perhaps to divert the traffic through a proxy server, but these are all far more difficult than tapping a normal phone.
Calls between a PC and a regular telephone via the SkypeIn or SkypeOut service, however, could fall under existing wiretapping regulations and capabilities at the point where they meet the public telephone network.
The pan-European response to the problem may open the door for the US to take similar action, Thuy said.
"We have very good cooperation with the US," he said.
The NSA is so concerned by Skype that it is offering hackers large sums of money to break its encryption, according to unsourced reports in the US.
"Investigators are convinced that the interception of telephone calls have become an essential tool of the police, who spend millions of euros each year tracking down crime through wiretaps of land lines and mobile phones," Eurojust said.
The first meeting of Eurojust's 27 national representatives is planned in the coming weeks but precise details of its timing and the location of the meeting remain secret, Thuy said.
"They will exchange information and then we will give advice on how to proceed," he said. Bringing internet telephony into line with calls on land lines and mobile phones "could be the price we have to pay for our security," he said.