Thanks ianobi, That's what I thought so too.
But since you are referring that the problem might already exist almost 3 years, do you think there's a change that OBIHAI is going to fix this?
The problem might be even worse, because as you stated, the OBi202 is only bridging the sessions, not terminating, so the OBi should only suggest the codec(s) offered from the calling party to the callee. The strange part is that it also offers, albeit at the lowest priority, its preferred PCMU. Even disabling the PCMU codec on the OBi altogether it still starts its RTP sessions in PCMU.
I will inform their technical support and hope this might be an easy fix.