You are able to register up to 15 wireless users on yourMB300ES base. The limitation of 4 that you are referring to in the manual isthe number of wireless beltpack users that can talk (transmit) back to everyoneat the same time. All 15 beltpacks can listen at the same time but only thefirst 4 users talking (transmitting) will be heard. If a fifth user wants totalk they will need to wait till one of the 4 (talk paths) stops transmitting.It’s a rotating 4 based upon a first come first served basis for all 15beltpacks. Your beltpacks can be programmed to operate in hands free mode or pushto talk to help manage the 4 talk paths. If you indeed need more than 4 people talking at once thenyou would need to add an additional base to increase the number to 8.