Vested interest alert because Holdan Distribute Teradek in the UK, but I have just tested the Teradek Cube with a usb Vodaphone 3G modem and streamed the result live to Livestream. This was by plugging the USB Modem directly into the Cube and no computer was needed. I could even start and stop the stream using a button on the Cube.
This means streaming to anywhere in the world from a Camcorder the field or literally a field, as long as you have a half decent 3G Signal. I had 3 out of 5 bars.