iPhone 4 ringer not working

I've searched around but havent had much luck solving this problem:

frequently the ringer will just stop working. The phone still vibrates but the ringer doesn't make a sound. If I try to listen to music, the sound won't work unless I turn the volume to max. After that, I can turn the volume to a normal level and the sound and ringer will function normally for a period of time.

Before you ask, no, the silent switch is not engaged.
Also the phone does not say that there are headphones plugged in either.

Anyone else solve this?

chefkid said:

make sure the switch on the side is the white side, and if that doesnt work try restarting your phone.

Click to expand...

Thanks for the tip. I actually just took it to the apple store and they gave me a new phone. Works better now.