I have an Obihai OBi200 1-Port VoIP Phone Adapter. For many months, it is been working fine. Today it will provide a dialtone and you can dial a number (and I have tried many). It rings then it will then give you a message that it can't connect. However, using the Google voice app on my win 10 laptop, I can connect to those same numbers without a flaw.
I have rebooted it several times and it gives the same result.
I tracked down the problem. For some reason, my device became unconfigured. I have started a reconfigure but it's a little progress wheel went around for about 20 minutes. It finally came back to "off Line"