NEC in Japan reckons that the increasing popularity of VoIP (Voice over Internet Protocol) telephones is about to lead to a surge in nuisance calls from marketeers or worse and so has developed technology to block unsolicited diallers from getting through.

The VoIP SEAL software sits on server computers and uses a Turing test to determine if calls crossing the network are real or are pre-recorded messages that have been generated automatically in much the same way spam email is created.

NEC claims a 99 per cent success rate in filtering out such junk calls, which it believes must be tackled if VoIP technology is to gain full market penetration. After all, no one wants a constantly ringing phone spewing out adverts for Viagra or demands that bank details be sent to Nigeria.

Apparently, the new wave of unwanted calls has already been dubbed SPIT, which stands for Spam over Internet Telephony, in case you hadn't guessed.