📦 Description: 
The Grandstream GBX20 is a professional extension module designed to expand the functionality of Grandstream GRP series IP phones. It provides a large color LCD display and 40 programmable extension keys per module, making it ideal for receptionists, call centers, and enterprises that require efficient call handling and monitoring.

⚙️ Details:

• Product: Extension Module
• Brand: Grandstream
• Model: GBX20
• Display: 272 × 480 pixel color LCD
• Keys:
  • 20 dual‑color programmable keys per page
  • 2 pages (40 keys total per module)
• Expansion:
  • Up to 4 modules can be daisy‑chained
  • Maximum of 160 programmable keys when fully expanded
• Compatibility: GRP2615, GRP2624, GRP2634, GRP2636, GRP2670 IP phones
• Features: BLF, speed dial, call transfer, call park, and other programmable functions
• Power: Powered directly by host phone (no external PSU required)
• Application: Reception desks, call centers, enterprises, and professionals managing high call volumes