Google Voice two-factor authentication is fine, and it will not interfere with, nor stop you from setting up Google Voice on an OBi. The new OBi<-->Google Voice authentication method exchanges secure tokens with your OBi, after you log into your own Google account. The OBi itself, never logs into the account, so it doesn't know nor need your password, nor 2FA. You are instead giving the OBi permission to use the Google Chat service on your account, via the encrypted access token stored on the device.
You
cannot do this from the OBi's local web page interface; you must use the OBiTALK web portal.
Carefully read and follow my instructions, here:
http://www.obitalk.com/forum/index.php?topic=8560.msg56460#msg56460An OBi 200 can be configured with up to four different Google Voice accounts, on SP1 through SP4, respectively.
The key to success is to be sure you are logged into the correct Google account, when performing the procedure in my link.