General
Colour	Black
Length/depth	33.5 mm
Number of LAN ports	2
Display resolution	272x480 Pixel
Display type	TFT colour LCD
Current supply	PoE, mains
Power adaptor	12 V/1 A
Headset connectivity	RJ9
Number of keys per module	40
Maximum number of modules	4
Maximum number of contacts	160
Compatible models	GRP2615, GXV3350, GRP2624, GRP2650, GRP2670, GXV3450
Firmware update	via host telephone
Touch display
Display backlighting
Hands-free function
Optical call signalling
Connection plate
Stand foot
Screws
USB cable
Quick installation guide

The Grandstream GBX20 is an expansion module for IP phones that provides additional functionality and operating comfort. The module extends the user interface with a 4.3-inch TFT colour LCD display with a resolution of 272x480 pixels, which is designed as a touch display and equipped with display backlighting. This enables clear visibility of all functions, even in poor lighting conditions. Operation is performed via dual-color buttons, arranged on two sides, with each module providing 40 keys. By cascading up to four modules, a total of up to 160 contacts and function keys can be supported. The display includes functions such as BLF status, speed dial, presence, intercom, conference, call park/retrieve, call forwarding, and more. The functions remain visible on the display even with multiple connected modules.

Applications
The GBX20 is designed for companies that need to manage a high number of calls and contacts. It is particularly suitable for call centres, administrations, or offices with complex communication requirements, where quick access to many functions and contacts is necessary. The expansion enables more efficient use of IP phones, especially for users who frequently switch between different call states, conferences, or contacts.

Functions and equipment in detail
The module features a speakerphone function and optical call indication, which visually signals an incoming call. Headset connectivity is via an RJ9 connector, enabling use with standard headsets. Power supply can be via PoE (Power over Ethernet), or alternatively via an external power supply using a 12 V/1 A power adapter. When using multiple modules, external power supply is recommended. Firmware updates can be performed directly via the host phone, simplifying maintenance and updating.

Technology explained simply
The GBX20 operates as an expansion module and connects to the main phone, thereby extending its functionality. Communication occurs via LAN ports, with the module having two LAN ports. The connection is made via a USB cable, which is included in the delivery. Cascading up to four modules allows flexible expansion of the user interface without impairing the functionality of the main phone. The display shows all relevant information, so the user always has an overview of call status, contacts, and functions.

Compatibility and accessories
The connection is made via a connection plate for the phone, included in the delivery. Installation is done using screws and a stand foot, also supplied. Power supply is either via PoE or via the included 12 V/1 A power adapter. Firmware updates are controlled via the host phone, enabling central maintenance.

Installation and mounting
Installation is performed by connecting the module to the main phone using the included connection plate and screws. The stand foot ensures stable positioning. The USB cable is used for data transmission between module and phone. Power supply can be via PoE, with the external power supply recommended for multiple modules. The short installation guide included in the delivery assists with setup.

Operational advantages
The GBX20 offers a significant extension of the user interface, accelerating workflows. The ability to manage up to 160 contacts and functions via a touch display with backlighting increases efficiency. The combination of dual-color buttons and visual display enables fast and intuitive operation. Support for BLF, conference, and call parking simplifies communication in complex environments. Firmware updates via the host phone reduce maintenance effort.

Colour and dimensions
The module is finished in black and has a height of 210 mm, width of 124 mm, and depth of 33.5 mm. Weight is 360 g. The compact design allows flexible placement at the workstation.

Delivery contents
The product is delivered with the GBX20 expansion module, a stand foot, a connection plate for the phone, screws, a USB cable, a 12 V/1 A power adapter, and a short installation guide.