I have a CME 12.0 system and it works as needed and this system has a public IP address. I set up a system for a friend at my site and used a public IP and it too worked correctly.
But, when we installed it at his site, it too works correctly; sort of. The CWF and SNR calls go through but there is no audio in either direction. Calls to/from the CME system work fine, just the hairpin calls loose audio.
I had the same problem at my location when I had a dynamic IP address provided by Verizon wireless Internet. The second that I had Verizon wireless set me up with a static IP (at a cost of $500!), hairpin calls worked perfectly. Both parties could now hear each other. And NO changes were made to my configuration.
My friends system is behind a Cox cable modem does not have a static IP and their system is doing the same thing. No audio on calls that come into his CME and then are call forwarded or single number reach to an off-net number.
Any idea how we can get their system to work on CFW/SNR calls without having to get a static IP? To me it seems that the RTP packets are getting lost. The config is basic CME. His system only is used for the CME. His computers are on another system off the Cox system.