This information is available in the Broadcaster FAQ in the Livestream store
Below please find the list of supported US Modems:
Verizon Pantech UML290
T-Mobile Jet 2.0
AT&T USBConnect Momentum
Clear Stick Atlas
These modems were all tested with their latest firmware. Please be sure to install all latest upgrades for the best compatibility.
Many more modems will work with the Livestream Broadcaster, including international carriers, but we do not officially support them at this time.