Forwards calls to Google Chat is an important option for people who are using Google Voice as free VOIP solution. In order to able to receive calling, forwards calls to Google Chat option must be activated so the VOIP adapter can acts as a Google Chat to receive calling, eg: OBi Devices. Without that, the phone will never ring when people call your Google Voice number.
If the Google Voice Account was newly set up, in default the “Forwards calls to Google Chat” option is inactivated. Google didn’t provide any selectable option for adding the option to Google Voice.
Here is how you can add Google Chat to the “Forwards calls to” list.
Full article here:
Quick trick for Missing Forwards calls to Google Chat Option in Google Voice Account (ALL4OS)