I have tried to get VVM to work for over 2 years on both iPhone 4 and now on iPhone 5s. Because of work, my phone has to be unlocked so that I can exchang microsim (now nanosim) cards when I go over the border. I have been doing this for nearly 2 years. AT&T is the US carrier and Rogers was the Canadian one.
After many hours with Roger's technical support, I finally found an honest person who told me that "Rogers only supports VVM on the iPhones they sell." I asked how they could tell and they said via the IMEI number. So, they are DELIBERATELY not supporting a feature of Apple's iPhone when purchased from Apple or any vendor other than Rogers.
I have now complained directly to Apple's management as I believe this may be in violation of the contract. My AT&T representative believes it is. In any case, it sure stinks from the point of view of an end user who buys from Apple.
I finally gave up and switched to Koodo which supports VVM just fine. Leave Rogers and you will get better coverage, better support for features, and more honesty.
While that is true, some unlocked iPhones will work just fine on VVM on Rogers. Also no they are not violating the contract as Apple and Rogers have contracts between them which they write down and all way before the phones and services are out.
I have a factory unlocked iPhone 5S which my sister got my and when i used it a bit, VVM worked just fine.