- 8 lines 4 SIP accounts - Integrated Bluetooth to connect headsets sync contacts calendars and more -EHS support for Plantronics headsets and USB to support Grandstream�s GUV Series headsets -Compatible with the GBX20 Extension Module that adds functionality versatility and flexibility with up to 40 contacts per module and support for up to 160 contacts by connecting 4 extension modules - Full-duplex speakerphone with HD audio to maximize audio quality and clarity - Equipped with noise shield technology to minimize background noise - Dual switched autosensing 10/100/1000 Mbps Gigabit Ethernet ports with integrated PoE - Supports 5-way audio conferencing for easy conference calls - Enterprise-level protection including secure boot dual firmware images and encrypted data storage - Wall mount sold separately