Question : SIP Proxy Server

Hey Experts,
I have a VCX Connect phone system which does not work good with external nat without a VPN tunnel.  I am looking for a SIP Proxy which handles this NAT.  I tried setting up a OPENSIPS server but am not a linux guy at all and did not have much success with this.  Anyone have an idea on how i could do this?  Open source is good!

Answer : SIP Proxy Server

Sounds like you would need to look at this page too:
http://www.brekeke.com/products/products_sip_nat.php