I'm assuming that you are using Google Voice. If not, who is your VoIP provider?
With the OBi shut down and you call from Gmail, do you have the same problem? If so, it's obviously not related to the OBi; post details about your ISP, modem, router, etc.
Does your dial tone have pauses?
When you call the echo test **9 222 222 222, does that have pauses?