When connecting multiple Whozz Calling? POS 4 line models together set DIP switch #8 to ON. The DIP switches 1-3, used to set the correct line numbers for each unit, will increment line numbers by 4 instead of 8. For example, the first 4 line model would have DIP switch #8 ON (and #1,#2 & #3 OFF) to set it for line numbers 1 through 4. The second unit would have #8 ON, #1 ON (and #2 & #3 OFF) for lines 5 through 9.