The ITC-200E provides an additional 8 channels to the Datavideo ITC-100 tally/talkback system. This ITC-100/ITC-200E combination effectively gives you a 15 channel system. The ITC-100/ITC-200E combination enables the operator to talk to the channels 1-7 separately and the other 8 as a group or to all 15 channels at once.