However, when the callers who are directly forwarded to my cell phone (second rule) doesn't work properly. My cell phone rings when some one calls and when I pick up the phone I am not able to hear them. Also, for the callers the phone is always ringing.
I think you'll find this has nothing to do with InboundCallRoute rules and routing. This is more likely a problem with NAT issues and your router. If possible, temporarily bypass your router by directly connecting the OBi to your modem. Power-cycle both devices after making the direct connection. Then create the problematic scenario again. If the audio problem is gone, it's a router issue.