After 4 years of using a OBI 200 over ATT Uverse, the unit stopped connecting to Google Voice. I had done nothing to change the configuration. Re-installed the unit several times, and was never able to connect. The echo test (**9 222 222 222) worked fine. I moved the unit to a different house using Spectrum internet, and the unit connected without any issue.
The OBI status shows "SP1, Google Voice, Connect Failed: No Response". The OBI200, ATT router, OBI dashboard, and Google voice do not show any other error. I have no idea what has changed.