Sorry - it was late when I posted. The setting I spoke of was in GV.
This morning, still no go on Obi. But I asked Alexa to dial each of them using my GV number - including non-emergency fire dept, which Obi also rejects - and all went through.
So it's not the numbers, GV or my cell. This is an Obi 200 problem.
Thinking back a few weeks - when the GV/Obi token error got (temporarily) resolved, I remember calling City Hall the day after and getting the same error response. I immediately thought the Token thing was back, but since other numbers went through, I forgot about it. Till last night.
Don't know if this is part of the original problem, something broken by the 'fix' or something else. But if I had to guess, it would be that it will magically work again when Poly finally gives us that firmware update.
Till then, thank goodness for Alexa.