Audio Only Master Station - The AX-8M is an audio only master station for the AX series. The unit is CAT-5e homerun wired to it's CEU and features an oversized TALK button to activate the VOX or PTT style communication, door call-in indicator, call button for other master stations in the system, a call tone volume control and a button for door release. The AX-8M can communicate to 8 masters and 8 door stations. Add-on selectors (AX-16SW) can be added to increase the number of door to a maximum of 120.