I fixed the ATA 186 problem. Please try this out. If you are behind the router (say Linksys), better use the Static Ip. I am using a LINKSYS router whose DHCP range starts from 192.168.1.100 . So decided to use 192.168.1.54 as static Ip and i made the ATA to work in its static mode (20#0#3). Then i assigned the static Ip, Default gateway (192.168.1.1) and Subnet mask (255.255.255.0). Once done with this. Goto your router setup page (i assume that people are using Linksys router). Goto “Advanced” tab, then “Forwording” . Please check with your PC2PHONE service provider about what PORTS do they use (like SIP, Media Ports). My service provider Use SIP port 5060 and uses Media Ports 20000 and 20001 (normally the range is between 16000 and 32000). To these ports of your ATA’s IP address, you have to forward the incoming data (voice) from the Router. Also enable the UDP. Also you have to disable the DMZ HOST (i.e enter the ip address as 192.168.1.0). Please try this one out and let me know.