Help Galaxy S3 sends text when switched off?

[anpease]

Hi,
I've never had this happen before, but when my phone was turned off yesterday morning my friend tried to phone me and left a message on voicemail for me, as would usually happen.
However, this time she received a text message back saying that I was in a meeting and would call her later, and it definitely came from my phone.
I wasn't aware the phone could do this, does anyone know how I turn this option off? (Samsung Galaxy S3 i9300)
Many thanks.

 

[Mikestony]

Go into your phone dialer..hit menu and then go to call settings....then call restrictions and turn the "auto reject mode" off.
I didn't know either that with the phone off, that it would send a message.