Nokia 6234 keeps beeping......

Hi Guys, hope you are well. Just a quickie, my dads Nokia 6234 keeps beeping every few minutes or so for no apparent reason. He does however have bluetooth turned on all the time as he uses the phone in the car with a Parrot bluetooth car kit which it also beeps through every few minutes.

Any ideas would be greatly appreciated.

Thanks in advance.

Dominic

nokia 6234,i no use