Skype, which is owned by eBay, integrated software by Israeli company KishKish into its services as a paid-for add on. The software analyses voice patterns and tells a caller when it thinks the other party to a conversation is lying.

But Sue Cullen, a privacy specialist at Pinsent Masons, the law firm behind OUT-LAW, told weekly technology podcast OUT-LAW Radio that users could easily find themselves falling foul of the law.