Vang Vieng Intl. Bus

I've heard there is an Intl. bus running from Vang Vieng to Udon Thani. Does anyone know where I can catch the bus in Vang Vieng and when it goes? Does it stop in Vientiane? Thanx

Yes. There are buses and minibuses leaving Vang Vieng for Nong Khai and Udon Thani. I took a VIP-Bus that leaving VV 10 am. and I was in Nong Khai 3 pm. One hour more for Udon Thani. It stops in Vientiane. Bought ticket near Saysong Guesthose near the tubing operators.