Lina:
it seems you use the Obitalk portal. You just need to adjust step 2 of what the Obi support told you as shown below;
2. Under Voice Service SP1 Service, change the InboundCallRoute to: {PP(123456789),ph1}
This would ring the physical phone connected to the "phone 1" port at the back of the obi202,
and would also ring the Obion app running on the android phone and that has the Obi number "123456789".
Substitute the "123456789" string, with the one your Obion app has.
@MurrayB: yes, that's my understanding even though in her latest response stated that she'd like
to have the call forked to the Obion app. In either case, the changes are very similar.
L.