SIP Gateway

I need to setup a SIP gateway. Simple put i need to accept a SIP call from the inbound SIP truck form any DID and send that DID to the outbound SIP trunk.

And ideas where to start.

That is not a SIP gateway as normally understood.

Whilst you could do this with Asterisk (in which case there is nothing particularly difficult and you should be able to do it from the available documentation), this only really needs a proxy. You may even find your router has SIP proxy support.

Why do you need this gateay? Most people manage to use a simple NAT router.