I am having some of the same issues experienced by Agent88 on 11/07/2015 - using the Obi202 for faxing faithfully for several months without issue. Suddenly a change in function. Now when dialing out with Canon4890dw fax (set to 7200bps, with ECM off & using Google Voice for dialing out on my SP2), the receiving fax line initially picks up, but is immediately disconnected. No change to any equipment on my end - and my previously flawless setup doesn't work anymore.
I've done my research on the forum, used the settings from the post by GSonFreephone from 09/18/2015.
I've played with the Obi Expert Configuration - turning off the ObiTalk settings, and the Device Default settings on all but the CODEC G.711U (with silence suppression enabled).
I'm certainly not experienced with SIP setup, but I am a willing student.
I welcome help from the Gurus out there. I promise to speak with civility and appreciation for any kind support.