To be clear, do you mean "I made an outbound call from the phone plugged into my OBiTALK device, and the party I called does not see my Google Voice number's caller ID on their display"?
If so, then this is because you are calling from a Google account that doesn't have its own Google Voice inbound phone number, so there is no caller ID number to send.
Either you don't have a Google Voice number, or, you set up the device while signed into some other Google account, and that account doesn't have a number.