A serial sex offender who bombarded a female driving instructor with filthy phone calls was jailed for five months on Wednesday.
Ian King was already on probation for a sex attack when he targeted the instructor after finding her mobile phone number listed in the Yellow Pages.
A sheriff yesterday criticised her lack of powers and said King would not be monitored when he was freed from prison in less than three months time.
Despite never meeting her face-to-face, King began leaving messages for her which became increasingly graphic and distressing, a court was told.
King told the woman she had a nice voice and then said he was going to dress her up in kinky underwear and perform degrading sex acts upon her.
The woman - who had no idea King was already on the Sex Offenders Register - recognised his voice from their initial call and contacted the police.
Sheriff Margaret Gimblett said: "What worries me is that you just don't seem to realise how serious your offending has become.
"The reports I have on you are very worrying. It seems you think you know better and are blaming those trying to help you rather than recognising you are very much at fault.
"It bothers me that you are deemed to be a high risk - yet you appear on a summary complaint on a breach of the peace charge. That means I cannot impose some form of supervision afterwards."
The Sheriff jailed King for five months and placed him on the Sex Offenders Register for seven years.
King, 23, from Dundee, admitted that for four months between November 2008 and February this year he broke the peace by phoning the woman and also leaving indecent messages.
Perth Sheriff Court heard how King initially contacted the woman about a driving lesson.
He contacted her again some weeks later and she recognised his voice. There was no discussion about driving lessons and he was keen to be involved in a personal conversation with her, so she hung up the phone.
At the beginning of February the woman had received 20 missed calls and five messages from the accused in which he made offensive and directly sexual remarks.
The messages, which the police later recorded were of an explicit nature, referring to her having sex and what she should wear.
King's own solicitor, John McLaughlin, said public safety was of "paramount importance" and the case had caused "significant concern". King has convictions for sexually aggravated assault in 2004, 2007 and 2008.
