Okay I did it. What should I do the next to get the logs? Sorry I never done it before.
You need to follow the steps written here:
viewtopic.php?p=80667#p80667
1) You need the syslogd.exe executable from the Internet Archive (unzip the file to extract syslogd.exe)
2) Enable logging of SIP Messages for the SP that's being used for Freephoneline.
From the OBi ATA's webUI, navigate to the SP1 Service (or SP2, SP3, or SP4 Service) setting that's being used for Freephoneline.
Change the "X_SipDebugOption" parameter to "Log All Messages."
3) From an elevated (admin) command prompt where the syslogd.exe file is located, run "syslogd -nl -s=all" without the quotation marks.
Open the Start Menu: Click the Windows Start button or press the Windows key.
Type "cmd": This will initiate a search for the command prompt application.
Right-click Command Prompt: Locate "Command Prompt" or "Command Prompt (Admin)" in the search results.
You want Command Prompt (Admin).
Otherwise, right-click on it.
Run as administrator: Select "Run as administrator" from the context menu.
Confirm UAC prompt: if prompted by User Account Control (UAC), click "Yes" to allow the application to make changes.
You may not need an elevated command prompt. I can't remember. I always use one by default.
4) Reboot the ATA. Receive an incoming call. After the call ends, exit syslog. You should find a text file with the contents of the log.
The problem is if RTP packets are never received, and if everything is basically being dropped due to CGNAT, I doubt the log file is going to be terribly useful. It's not always easy to analyze what you can't see. "Oh hey, look: you're not receiving stuff you need to receive." I already knew that (unless you are receiving data and the ATA is borderline wrecked). It's possible something useful will be shown. I'm just a little skeptical.