"jailbroken" 2g iPhone with no ringer.. Help

[Jkov]

I was given this phone by my brother and everything works great except there is no ringer when receiving incoming phone calls.. When playing music from iPod or choosing a ring tone, all sounds and speakers work... No keyboard click also.. I've checked and rechecked settings to assure I'm just not being a moron. I do however hear the ringer when I have my phone plus into my car stereo through the headphone Jack. It'll ring once or twice after the music fades and then will vibrate like it normally does... I don't get it, is it stuck in silent or is it something with the actually software. Please help