I can't hear ringing tone on iPhone 4
Help!My iPhone 4 with iOS5.0.1 was working fine till a few days ago.I can't hear ringing tone when I call somebody(even voicemail)or the person answering the phone.And when I want to disconnect the call I'm making-'cause I'm not hearing anything,the screen just freezes saying "ending"(call).I have to restart the phone to end the call.No problems with people calling me and messaging,e-mails,listening to the music etc.I tried with headphones as people were suggesting,tried restarting and rebooting the phone thousands of times and still nothing.Any ideas?
iPhone 4, iOS 5.0.1