A stalker subjected a woman and her friends to a nine-month campaign of terror, which included tens of thousands of abusive phone calls and text messages.

A jealous stalker made his victims’ lives hell, making tens of thousands of threatening phone calls and text messages over many months.

Deliver driver Theofillus Sugiaman became so consumed with jealousy when he discovered his casual lover had other boyfriends that he began a terrifying campaign of fear against her and her friends, a court heard on Friday.

The Brisbane District Court was told the married 41-year-old met his female victim on an internet dating service in March 2012, when she was 21.

She slept with him in exchange for cash or gifts, but the infatuated father of three soon became suspicious and gave her a smartphone installed with tracking software, which also enabled Sugiaman to access the woman’s address book and monitor her phone use.

He began stalking two other men she was seeing, several of her friends, and eventually the woman herself, as well as complete strangers.

When she moved house and new residents moved in, Sugiaman began stalking the new residents, the court heard.

Crown prosecutor Deborah Holliday said 15 victims were abused and threatened with violence or death repeatedly via phone or text. Sugiaman told them he knew where they lived and sent numerous taxis and pizzas to their doors.

In the worst case, he called one victim 10,636 times over six weeks, averaging 240 calls a day.

He used online software not only to disguise his phone number but make it appear as if the abusive calls and text messages were coming from the 21-year-old woman or others.

Ms Holliday, he implicated them in numerous hoax bomb threats and calls to emergency services, making the woman’s life “hell” and distressing her friends.

Police subjected the distressed woman to hours of questioning until they finally tracked the real perpetrator through one of his phones.

Sugiaman’s barrister, Andrew James, said his depressed client had at the time recently lost custody of his children and became delusional.

Judge Michael Shanahan sentenced Sugiaman to the maximum seven years imprisonment, saying the large-scale harassment had disrupted lives and tied up police resources.

“In my view (it) is one of the most serious examples of the offence of stalking,” he said.

the judge also placed restraining orders preventing Sugiaman going near his victims for 10 years.

Sugiaman has already served more than a year in jail and will be eligible for parole September 2015.

Mr James said Sugiaman hoped to move back in with his mother at Slacks Creek, south of Brisbane, after his release.