I received this e-mail today. The answer is that I have not gotten the DVG-1120M to work behind my router. I tried and gave up. AT&T's Gary Morgenstern told me at the time that you couldn't put this device behind the router. I recall he mentioned in the future you would be able to. Hopefully we will get some feedback on this post to resolve this question.
Hello Mr. Tehrani,
I read your article about the LNP and Call Vantage. I assume you are probably using D-Link DVG-1120 M. If so, have you ever tried connecting your TA behind a Router. Has it ever worked. I have spent countless hours with the AT & T reps and D-Link reps and apparently nobody seems to know what is wrong and / or how to fix the problem.
After several hours of my testing (with little knowledge in these areas), and countless hours with the customer service on the phone, I decided to turn to people who have successfully implemented this and using it.
I am sorry, If I took you away from your busy schedules with this email. If you could please help that would be great.