Grandstream GBX20 EXT Extension Module for GXV3350 and GRP2615 IP Phones

The Grandstream GBX20 EXT Extension Module is designed to streamline high-volume call handling for professional environments. Ideal for receptionists, administrative assistants, call center supervisors, and executives, the GBX20 provides a powerful expansion interface for Grandstream IP phones like the GXV3350 and GRP2615. Featuring a vibrant color display and up to 160 programmable keys with multi-function support, this module enhances call visibility, response speed, and user efficiency in busy communication hubs.

Product Features

High-Resolution Color Display

The GBX20 features a 4.3-inch TFT color LCD with a 272 x 480 resolution that delivers clear, easy-to-read visual indicators for all programmable functions. Dual-color LEDs display real-time line status for each key, improving call management visibility.

Programmable Keys with Multi-Page Support

Each module supports 20 physical keys with dual-color indicators and two page views, providing access to up to 40 extensions or features per module. Users can configure keys for functions such as Busy Lamp Field (BLF), speed dial, call park, pickup, presence, and intercom.

Expandable up to 160 Keys

The GBX20 supports daisy-chaining of up to four modules, offering a total of 160 programmable keys. This modular approach allows users to scale their system as their call traffic or staffing needs grow.

Seamless Compatibility

Fully compatible with Grandstream GXV3350 and GRP2615 IP phones, and select models such as GRP2624, GRP2650, and GRP2670, the GBX20 integrates tightly with the phone interface to provide consistent, responsive control.

Simplified Power and Connectivity

When using a single GBX20 module, power and connectivity are provided directly from the host phone. If more than one module is connected, an external 12V/1A power supply is required for stable performance.

Centralized Configuration and Firmware Management

The extension module is configured and managed via the host phone’s interface, simplifying network provisioning, firmware updates, and key assignments. This reduces IT workload and ensures smooth deployment across offices.

Advanced Call Handling Functions

Designed to improve workflow in high-traffic environments, the GBX20 supports advanced telephony features like call transfer, call forward, voice conferencing, speed dial, and call pickup — all accessible through one-touch keys.

Product Specifications

• Display: 4.3-inch TFT color LCD, 272 x 480 resolution

• Programmable keys: 20 per page, 2 pages per module (40 total per module)

• Maximum expansion: Supports up to 4 GBX20 modules (160 keys total)

• Compatibility: Grandstream GXV3350, GRP2615, GRP2624, GRP2650, GRP2670

• LED indicators: Dual-color (red/green) for line and feature status

• Functions supported: BLF, speed dial, call pickup, call park, presence, intercom, call transfer, call forward

• Connectivity: Connects to host phone via USB; additional modules require USB and power passthrough

• Power: One module powered via host phone; multiple modules require external 12V/1A power adapter

• Firmware and configuration: Managed through host phone’s interface

• Dimensions: Approx. 210 mm × 124 mm × 33.5 mm

• Operating temperature: 0°C to 40°C

• Humidity: 10% to 90% (non-condensing)

• In the box: GBX20 module, USB cable, stand, connector bracket, screws, quick installation guide