I am having the same problem with my Obi200, and have tried numerous fixes that I've come across in the forum, but honestly i'm not sure i know what I'm doing.
I connected the ethernet cable directly to the modem i have from Spectrum, an ARRIS TG1672G.
Multiple attempts to configure the device end up with a message, backing off TCP connection failed
I can get the IP when i call, but when i try the echo test there is silence.
Google voice is working, as all the calls made to the GV number are going to the linked cell phone - but i am unable to get the phone connected to the obi device to work.
Any suggestions are greatly appreciated!!!
Thanks