A man who tried to have sex with three under-age girls was in for a shock.
It turned out the "youngsters" he chatted to online, aged 12 and 13, were actually paedophile hunters.
Derek Cox, 59, of no fixed address, pleaded guilty to three charges of attempting to communicate in a sexual manner with a child.
Judge Euan Ambrose jailed him for six months.
He told Cox: "There were no real children.
"The people with whom you communicated were adults posing as children for the purpose of bringing individuals like yourself to justice."
Cox was handed a seven-year Sexual Harm Prevention Order banning him from unsupervised contact with children aged under 16 and unchecked internet use.
He was told to register as a sex offender for seven years.
Bristol Crown Court heard Cox messaged three "girls" online.
One told him she was called Lacey Lou, 12, from Manchester.
Two others, Sasha and Shelley, both said they were 13 and from Sheffield.
Cox, who admitted being a lot older, used a false name as his chats with them turned sexual.
The court heard he invited them to Bristol and offered to meet the girls in Sheffield, saying he would book a hotel.
When he found out the Sheffield youngsters knew each other he wanted to engage in sexual activity with the two girls together, the court heard.
No meetings took place and Cox was confronted by paedophile hunters in Thornbury, where he was living at the time.
Edward Hetherington, defending, said his client had been under stress at the time.
He said the impact of vigilantes turning up to expose him had been considerable.
He added that the fire alarm services engineer had been a hard-working man who retained the support of his family.
