I followed the instruction from here:
6. To create a GVSIP trunk, choose Trunks -> Add SIP Trunk. Enter a Trunk Name and your Google Voice account name (without @gmail.com) for Username. Click Get Password for Google Voice button. Google then will prompt you for your credentials to login to your Google account. Once logged in, your OAuth credentials will be generated for you, and you will be returned to the Trunk template. Enter your 10-digit Google Voice number as Outbound CallerID. Set Maximum Channels and Maximum Outbound Channels to 2. Set Dial Rule to NXXNXXXXXX. Click Submit Changes and click the Red Bar to reload your dialplan. In the left column, your new GVSIP trunk should appear under the Trunks option. You can also verify the registration by choosing the Status option.
The registration is OK.
I can receive call but no way to call out,
always "ResetCDR" for any GV call.