Asus — my asus zenfone 5 is frequently having network problem and the call is being disconnected.

Address: Chennai, Tamil Nadu

Sir, I am not able to make a call to anybody. After few seconds of making a call there is a crackling sound and the call is disconnected. I am using dual sim. how to rectify this problem. I had used lower standard of mobiles so far and I have not faced such problem. Kindly rectify it.