For Viking- terminals
A Viking terminal can be recognized when the terminal is in default mode or in main screen and VIKING PA is displayed at the top of the screen. See picture below for an example of the main screen of a Viking terminal.
Now you can see your Terminal ID on the screen.
For OnePA- terminals
OnePA terminals are either Ingenico or Spire branded. You can identify a OnePA terminal if you have a “welcome” message on your screen or the terminal looks similar as the picture below.