The message left on the phone was addressed to his brother and says that he gives all that he has to his brother and nephew.
The unsent message detailed how to access the man's bank account details and where he wanted his ashes to be buried.
Under the state's laws, a deceased's next of kin - such as a spouse - becomes the manager of his or her estate if a will is not prepared.
An unsent text has been accepted as an official will by a court in Queensland, Australia.
The family feud over the status of the text played out in the Queensland Supreme Court as the man's brother and nephew asked for the message to be treated as his final will.
The man's wife took the case to the Brisbane Supreme Court to manage her deceased husband's estate.
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"It should be said, notwithstanding that the applicant had moved out, she still made arrangements to take the deceased to his mental health appointments and that they spent the weekend prior to his death together, cleaning garden clippings and boxing books for Lifeline", the judge said.
In her ruling, Justice Susan Brown said there were a number of elements in the unsent text message that suggested it was a will, such as instructions on where his ashes will be placed, as well as an order that his wife "will take her stuff only".
"Since the respondents stand to benefit if the text message is treated as a will, I have treated their evidence with caution and weighed it against all of the evidence".
According to the Australian government website Victoria Legal Aid, for someone's will to be valid, one is required to sign it in the presence of two witnesses.
"If a person hasn't drawn a formal will, there are some significant hurdles which must be overcome to establish that the document that looks like a will, is in fact, a will".