My Samsung Galaxy SII I91000 (unlocked GSM) has started making a horrible Gestapo-toned alarm at any hour of day or night unless it is turned off. The state of battery charge does not matter and it also happens when plugged in and charging.
I have never installed any alarm system nor am I aware of alarm functions on the phone.
I did have Prey installed, but have heard its alarm and it is nothing like this.
I have now uninstalled Prey and it still happens.
It often happens mid call, but the other party is apparently not deafened by it as I am.
The only thing I can do when it happens is to touch the WiFi icon at the top of the screen or put it in silent mode or shut it down.
I did change the SIM card a couple of weeks before this started, but the phone is unlocked anyway.
The new SIM is Movistar, an annoying Latin American company that sends many many text sales messages daily, but the notice of these messages is a sweet "chirp" and not this horrible squawk.
Any help is appreciated. I now have an "ear worm" consisting of this horrendous sound!