A Louisiana man was sentenced to six months in prison yesterday for infecting WebTV users with a Trojan that made nuisance calls to 911.

David Jeansonne, 41, of Metairie, La., pleaded guilty last month to causing a threat to public safety and causing damage to computers. On Monday, he was sentenced to six months in prison, and ordered to pay Microsoft more than $27,100. U.S. District Judge Ronald M. Whyte sentenced Jeansonne to serve an additional six months home detention., according to information from Sophos, Inc.

''It's good to see firm action being taken against another author of malicious code,'' says Graham Cluley, senior technology consultant for Sophos, an anti-virus and anti-spam company with U.S. headquarters in Lynnfield, Mass. ''Making prank phone calls to the police is a dangerous occupation, which could have life-threatening repercussions for innocent members of the general public. Writing a program to automatically cause this kind of nuisance demonstrates a whole new level of moronic behaviour.''

The WebTV service, now known as MSN TV, allows subscribers to connect to the Internet using their television. Jeansonne's Trojan horse was emailed to users in 2002. Sophos reports that the bug posed as a program which would change colours on their TV screens. However, the attached file reset the settings on the user's WebTV box, making it dial 911 the next time it attempted to connect to the Internet.

Approximately 20 users are said to have received the email, and 10 reported that the local police either telephoned or visited their home in response to the emergency phone call.