Review (3/5): If you follow the instruction set that is with the 4 person set all works well.
I already had a the 3 person communication set. I purchased another V4 set. I used the instruction set that is given with the 4 person communication set and all paired well. All 4 units were working fine. I turnd off all the sets and turned them back on and the V4 (1),V6(1) were still paired and the V4(2),V6(2) were still paired, but the set (1) and set(2) were not paired. I had to pair the units again. All 4 units do not hold the paring once powered down.