New Zealand Privacy Commissioner Marie Shroff says people should remember that it's illegal to hack into phones and listen to conversations, or get information from message systems.
She says doing so is the same as opening letters addressed to someone else, which is also against the law, as people expect their communications to be private.
A phone hacking scandal that's ended the existence of the Britain's News of the World newspaper is threatening to ensnare the Prime Minister David Cameron, with the arrest of his former press chief Andy Coulson.
Media mogul Rupert Murdoch has killed off the newspaper to try to stem the crisis that threatens to infect the rest of his empire.
Mr Coulson was the paper's editor of the paper at the time of the phone hacking scandal.
Mrs Schroff says it is advisable for people to lock their phones with a high quality password, because they contain a lot of information and can be lost or stolen easily.
She says people should look carefully at what sort of protection systems are provided on their phones.