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!)