UM.... I THINK THE FASTEST SERVICE IS THAT OF MERO MOBILE'S WIRELESS SERVICE... WHICH GIVES U SPEED OF UPTO 384 KBPS..... USING THE EDGE NETWORK.... BUT I DON'T KNOW IF VONAGE CAN BE USED WID WIRELESS...
UM.... MORE INFO IS ON THIS LINK...
HOPE THIS HELPS...
http://www.spicenepal.com/english/index.php?option=com_content&task=view&id=21