Well, so I've managed to set up bluetooth. Paired with a smartphone (Nexus 6).
However, eventually I had to unpair them because of poor quality of voice.
If I just use obihai to place voip calls -- it works excellent.
If I just use my smartphone to place calls -- it works excellent.
But if I use obihai to place smartphone calls via bluetooth then quality is not there. Unfortunately unacceptably low quality of voice via bluetooth.