Study the OBi202 dial plan here
http://ozarkedge.mypressonline.com/index.htm. The OBi way is elegant and cool, if you honor it. You can also easily reference digit map and call route syntax.
There is no error testing... a misconfigured OBi can crash/reboot, although I've not experienced this.
If you use OBiTALK Provisioning, it can overwrite settings made via the local web interface, and perhaps otherwise.