Australian Communications and Media Authority and the National Anti-Scam Centre have issued a joint alert warning of criminals taking control of mobile phone numbers or making unauthorised changes to accounts, then using access to reset passwords and drain bank accounts, myGov subscriptions and rewards programs.

The scam typically starts when a person's email account is compromised, or when scammers obtain ID documents or passwords through phishing or data breaches. Anyone with a mobile number is at risk, though people who suspect they have been caught in a data breach face higher danger. Warning signs include unexpected alerts about mobile account changes, unrequested verification codes, login attempts the person did not make, and a phone suddenly losing signal or switching to 'SOS only', Scamwatch reports.