Thought I had figured out why my Obi100 and Obi202 can't communicate on Obitalk (**9).
Based upon other threads, the Code 488 service provider rejection usually means a Codec mismatch. In every other discussion this has been about utilizing SIP providers rather than Obi's internal network between devices, but whatever.
Sure enough - these two devices DID NOT share any of the same codecs turned on in common! So I turned on the codecs on each that were turned off. Thought I nailed it. (I used to have really sad Internet bandwidth and had to play with codecs alot for call quality.)
No dice. Same Code 488 service provider rejection.

-- Michael