What is the difference between what U.S. attendees text to and International Attendees?

If your event is taking place in the U.S.:
U.S. mobile subscribers should text your event keyword to 66746.

International attendees (or those who have text message short code blocking on their phones), should text your event keyword to the virtual texting number we provided you.

If your event is taking place outside the U.S.:
Everyone should text your event keyword to the virtual texting number we provided you, even US mobile subscribers. 

The 66746 texting short code only works in the U.S. for U.S. mobile subscribers.
It's not our preferred way of doing things, but no one asked us the best way to do it! ;)