In order to make international calls from Obi phones, you must dial your Google Voice number first and then dial 2 when the auto attendant comes up. Then try entering 011, followed by the country code and phone number and dial pound (#). This should route the call through Google Voice. Although I have Google Voice running through FreePBX and finally an Obi1062, that method should work on any Obi phone using Google Voice as a service provider. Let me know if that works.
Sorry, but nope; that's not true. You can directly call any international number in locations supported by Google Voice/Hangouts. There is no need to call your own Google Voice number first, assuming, of course, that the dial string is valid.