I have an SPA-3000 at my house and an elastix server at the office. I am able to get the SPA-3000 registered and can place call just fine from the FXS port. However, I cannot receive calls. If I dial the extension of the SPA-3000 from another internal extension, I just get a fast busy signal. In freepbx it shows the remote IP address for the extension but says Unreachable for status. I AM able to use X-lite on my laptop from the same remote connection so I know I am configured properly and have the correct ports opened up. My router where elastix is has the following ports pointed to the elastix server: UDP 5004-5084 UDP 10000-20000 I have even tried opening these ports up on the remote router and pointing them to the spa-3000 but still no luck. The extension has the following settings: secret=mypassword dtmfmode=rfc2833 canreinvite=no context=from-internal host=dynamic type=friend nat=yes port=5060 qualify=yes If have also configered sip_nat.conf with the following: externip=18.104.22.168 nat=yes localnet=192.168.1.0/255.255.255.0 My spa-3000 device has the rtp packet size to 0.020, the asterisk IP as proxy, correct user id and password. It shows registered and I am able to make calls, just not recieve. And also, just in case you are wondering I have exited X-lite and was using it on another extension configured identically so there are no conflicts there. I am going crazy with this!! Any ideas?