They might be meant as fun, but pranks can end up with the prankster facing serious criminal charges, convictions and time in jail.

The issue is in the news because of the notorious prank call by a Sydney radio station to the London hospital pretending to be the Queen and Prince Philip asking about the Duchess of Cambridge. The High Court has found the Australian Communications and Media Authority had the power to rule that a radio station broke the law by recording and broadcasting the hoax call without the hospital employees' consent. Tragically, the hoax call went badly wrong when a nurse who spoke to the caller thinking it was the Queen later committed suicide. The two radio hosts involved in the prank have apologised for the prank and said they are devastated by the effect their prank had.

The radio station may also have broken the law under the NSW Surveillance Devices Act under which it is illegal to record a conversation without the other person's permission and to broadcast a recorded private conversation without permission.

There are many prank phone calls that can be considered criminal offences: Threatening to kill or cause serious harm to someone - and not just the person on the phone; Making a hoax bomb threat is a crime; Making prank calls to 000 pretending there is an emergency is open to jail time of up to three years.

Even if the prankster doesn't threaten their victim, repeated calls can amount to harassment, stalking or bullying. Under the Criminal Code it is illegal to use "a carriage service" (that includes phones, emails, texts and social media) to menace, harass or be offensive - with a penalty of up to three years jail.

If you are in this situation it would be wise to get legal advice to understand the options open to you. It may be possible to take civil action against the caller and seek damages under the tort of assault.

Police warn that if you receive a prank call you should not try to find out who the caller is by yourself because it may be dangerous. Police also warn not to retaliate by threatening the caller or to pretend you are a police officer when you receive the call, as this might assist their defence if it goes to court.

Prank calls and messages have been around for a long time and many are indeed funny and harmless - but it is when they exploit a person's vulnerability and trust that the prank can amount to abuse and bullying.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.