Reset any previous pairings
On the V4 (Coach) unit, press and hold the INTERPHONE/ON button until the LED flashes blue. Reset any previous pairings by pressing and holding both A and B buttons until the LED flashes red before switching back to flashing blue.
Connect the first two units
Press and hold button A on the V4 unit whilst at the same time press and hold the INTERPHONE button on the V6 (umpire) unit until the LED on both units are flashing red and blue continuously.
Press button A on the V4 unit - the LED on the V4 unit will flash blue as it seeks to pair with the V6 unit. When the units have paired, both units will flash blue. When this occurs, briefly press button A on the V4 unit to switch to talk mode.