Grandstream UCM6304A

Here’s a thorough and updated overview of the Grandstream UCM6304A IP PBX (audio-only variant):

    Key Specifications

• User & Call Capacity

  • Up to 1,000 SIP users

  • Supports 150 concurrent calls, or 120 when encrypted with SRTP 

  • Audio conferencing: up to 7 rooms, supporting 120 participants total 

• Analog Interfaces

  • 4 FXS ports for analog phones/faxes (lifeline support)

  • 4 FXO ports for PSTN trunks (lifeline support) 

• Networking & Expansion

  • 3× Gigabit Ethernet ports with PoE+, can act as router or switch 

  • Storage: 1× USB 2.0 + 1× USB 3.0, plus SD‑card slot 

  • Front display: 320×240 color touch LCD with shortcuts 

• Hardware & Performance

  • Built on Asterisk 16, uses a 6-core processor, 4 GB RAM, 128 GB flash 

• Security & Remote Management

  • Features secure boot, SRTP/TLS/HTTPS, unique certificates 

  • Supports Hot Standby High-Availability for failover 

  • Managed via GDMS (cloud provisioning) and remote connectivity through UCM RemoteConnect 

• Unified Communications Bundle

  • Includes Wave app for voice, messaging, conferencing on desktop/mobile 

  • Offers IM, auto-attendant (up to 5 layers), call queues, recording, fax-to-email, CDR, etc.