Phone spoilt

My iphone got some problem. When people phone me or when i call out, they cannot hear me, but i can hear them. This problem started few days ago, but because i rarely phone call people, so i didnt realised. No wonder these few days, all the call i picked up, the other side dont seems to hear me. Now i am left with my sms and whatsapp. But i am still able to make phone call if i use the speaker or use the ear piece. The problem only lies with talk directly using the phone by the ear. Ear piece and speaker mode both ok. So i am not very keen in getting a new one as iphone is so expensive. And i still can use the old one. And now there is no good data plan also. Shall wait until the whole phone cannot use then i see if i shall get one.