Hi there:
By default, calling your own Google Voice number from your linked mobile phone number assumes you want to access your Google Voice voicemail directly, not to ring your other forwarding destinations (OBi devices emulate Google Chat, which is treated as just another forwarding destination, like a 10-digit phone number).
To change this behavior, log into your Google Voice account from a laptop or desktop computer, not from your mobile device, and go here:
https://voice.google.com/settings.
Click the 3-bar "hamburger" icon in the upper left corner, then click "Legacy Google Voice", then click the gear icon to go to the Phones tab of Settings. Click the Edit button under your mobile number. On the next page, click "Show advanced settings".
On the next page, change "Voicemail access" to "No", and then click the Save button at the bottom of the page.
Now, when you call your GV number from your mobile phone number, the other destinations will ring. You can hit * to barge into your greeting and access voicemail if you wish, or just let someone answer the call. See the screenshot below.
As for the other direction, that sounds like a call forwarding loop. You can call your forwarding phone number(s) from your Google Voice number, but clearly, the call will go back to your GV voicemail or carrier voicemail if the phone is turned off, in airplane mode, busy or unanswered.