It appears nobody really offers this as standard... But why?
I remember when three mobile first launched, you were given two mobile phone numbers; one for voice and the other one for video. :? What a pain in the rear that was! One number for both voice/video calls sure did simplify things. Why not the same for VoIP?... Be nice to have one local geographical phone number to make and receive voice/video calls. OK so video calling on the three network (or any other) never took off but I'm pretty darn sure that's down to their expensive per minute charge. With third party apps such as Skype on your mobile and a data allowance i doubt mobile video calling will ever take off now.
Think about it for a moment... If VoIP suppliers offered video calling it would introduce people to the world of VoIP who would only otherwise continue to use apps such as Skype to call home. I know two people myself who Skype with their parents weekly due to living far apart yet they have never heard of VoIP and don't know what it can really do or offer them. :?
VoIP has been around for years now, it amazes me that only recently have they managed to reliably send data such as FAX over VoIP. I guess we will have to wait another 10 years or so for video.
I shall do a bit more reading on the subject in the meantime and I will check out the link above.