to get your nat to type 2 you will have to do some port forwarding within your router, This can be done from the internet browser on your computer. I can't tell you exactly how to do it because i don't know what router you have etc.
However there is likley to be a walk through set of of instructions on Port forward.com for setting up playstation network ports on your model of router
First you will need to find out what ip address the router has assigned your ps3. As it will be for this ip address that the changes need applied to.
http://portforward.com/
Heres the link good luck
But you have NAT type 2 and upnp is not available....... interesting.
KAV have you tried running your ps3 wired? I know when i ran my bluetooth headset and had my ps3 wireless i always came through garbled, so i switched to wired and now i'm only garbled when talking to several guys over the atlantic at once