How can I connect to a number with a conference-call code via Google Voice?
Evidently, the Google Voice app doesn't support conference codes or other extensions. (At least not yet.)

To call an extended number through the Google Voice service, dial as though the GV app weren't installed, or as if you were calling from something other than a smartphone:


Dial your own Google Voice phone number.
If voicemail access isn't enabled for the number you're calling from, press * to access the GV menu.
Enter your PIN, if required.
Press 2 (to tell the GV service you wish to place a call).
Enter the conference phone number, and press #. GV will connect you.
Proceed as normal for calling the desired number (i.e., enter the extension, the conference-room number, the passcode, etc.).


So, the contact is programmed with a number like this: 612-555-4321,[PIN,]2,800-555-1234#,,1234567890#. (As I understand it, this is a limited application of the process Flex Dialer uses.)

If you have the GV app installed, then use another app like Voice Plus or Voice Choice to exclude this contact from GV. (This is a consolation to what was originally asked for, which requested fewer exceptions to the phone's GV dialing rules. Shouldn't be a big problem, though.)

If you have your GV number associated with a contact for yourself or your voice mail, then that's the contact that will appear in your phone's call history. However, the "real" contact will show in your Google Voice call history.