iphone 5 internal headset not working

i got my iphone 5 just two months ago

i notes that the internal headset which mean the mean headset in the phone it self stop working with no reason

usually that is happening when i try to place a call , i cannot hear the other side . to solve the issue i use the speaker phone ..but i cannot keep doing that

i thought in the beginning that is maybe because the ear-set are not ejected properly ..

but it seems not the case .. so what should i do . and i don't have the apple care