My Cell phone shut off

I was waiting a call from a friend and was keep checking if she sent a message or I've missed a call. A friend will visit me today and baby Mac. Suddenly my phone went off and I didn't know why. It made me worried for a while but after taking out the battery and turning on twice its back again. Whew! Thanks God it is working now. Nways, I think she's here now coz I heard the door bell. Bye for now!