Wow, this was posted 3 years ago and still an issue.
I bought my obitalk (polycom branded) OBi200 late last year. On outgoing calls, normally the first of the day i get static once someone answers. There are no fax machines involved on either end. If i try calling back a second time the call usually goes through with out a problem.
I tried the setting change noted by 208ObiUser, fingers crossed this fixes it. It's embarrassing to have to constantly call people back.