I ran into same problem using obi200 w/ GV calling a line (Comcast). It happens 9 out of 10 times and that is the number I call the most. Before I bought obi200, I was using Asterisk with no problem over the same GV account and call the same Comcast number.
I did a week of reading on many forums, seems like many people have this problem since a few years, and Obi didn't have any solution, or even acknowledge this. Wish I knew before I bought it. Obi didn't reply to any of our question even in this forum. They didn't list it as a known issue in masking it from consumer. At this point I have no confident their engineering is competent in fixing this.
Yup, not a happy customer.