In Progress silent mode turn off itself after receiving/making a call

Nov 12, 2012
everything was ok for few months i've been using miui but now when i'm in silent mode and i receive or make a call my phone automatically turn silent mode off, i dont know why. eg. when i have silent mode and and someone call me two or more times, the second call is loud. please help me

my phone is se mini pro sk17i
have you checked the settings within the phone app and also settings volume/vibrate settings