I have my wrt54gp2-na behind another firewall (smoothwall) and have set it up to act as a simple router: no use of the wan, fixed IP, plugged in my network using the local interface 1. I have 2 other computers connected to it and a laptop using the wireless connection working just fine, using the DHCP on my smoothwall box. I tried everything I could do have the voip working with such a setup but can't have a connection to the sip server. I think the integrated ATA uses by default the wan interface. Am I correct? Any way I could route the sip calls to my existing lan? Another option would then be to setup the linksys to act as a transparent gateway, using the wan interface to connect to my existing lan. Any idea how to achieve this?