This sounds like a NAT issue... maybe we can try to walk through it:
1. What Device or SoftPhone are you using to make and receive calls?
2. In DDWRT:
-Enable UPnP
-Open and Forward port 5060 to the IP (private IP) of the Device/SoftPhone placing calls
-Open and forward the RTP port range for your device to your devices IP (the RTP port range used will vary based on what Device/Phone you're using eg. for a PAP2 this is 16300-16500)
-If possible set up STUN on your VoIP device
A few links that may help:
1.
http://forum.voxalot.com/voxalot-sup...t-routers.html
2.
http://forum.voxalot.com/voxalot-sup...html#post14452