How can a PACTOR modem or controller be used to determine if the channel is in use by other PACTOR stations?

  1. Unplug the data connector temporarily and see if the channel-busy indication is turned off
  2. Put the modem or controller in a mode which allows monitoring communications without a connection
  3. Transmit UI packets several times and wait to see if there is a response from another PACTOR station
  4. Send the message, "Is this frequency in use?"