How to disable mute button in call on 4s with iOS 7.1?

It happesn to me, and as far as I saw not only to me but to 90% of users, If I press my 4s with iOS 7.1 to my face when in call it mute's my call or turns the speaker on.

Is there a way to disable in-call buttons except keyboard?

Phone is original not Jailbrake