·Northland Cable ..
·Time Warner Cable
is the problem.
I had this problem too and had to spend quite some time getting my FW and NAT rules correct. You've got to port forward most of the UDP ports directly to your adapter.
Want to really rule out your FW? Put the adapter directly on your cable modem for a few hours and see how it goes.
Once my logs were showing clean on no port blocking the one sided calling thing went away on non-in-network calls.
In-network calls were another story.
Yep, tried all those. Different routers, port forwarding and putting the ATA after modem-before router. No difference. Plus, VOIPo have put me on different servers, updated my ATA firmware and swapped out ATAs. Still no difference.
Apart from Cox as my ISP with a SB6120 modem everything has been changed up and tried!
But tell me...
What logs are you referring to that showed no port blocking? Where was your port blocking occuring?
What is the other story about In-network calls?
Cox Preferred HSI 12/5~SB6120~Grandstrem HT502~FVS318G~WAP54G
OTA (...and proud of it!)