Grandstream UCM6304 IP PBX – 4 FXS + 4 FXO Ports, 2000 Users, 300 Calls & Video Conferencing for SMB Hybrid Communications The Grandstream UCM6304 is a rack-mountable hybrid IP PBX that brings together voice, video, conferencing, and collaboration tools in one secure, easy-to-manage appliance. It features 4 FXS ports for connecting analog phones and 4 FXO ports for PSTN lines, giving businesses a smooth path to modern communications while protecting existing investments and ensuring uptime with lifeline capability on every port. With capacity for up to 2000 users and 300 concurrent calls (200 secure SRTP calls), plus a powerful built-in meetings platform, the UCM6304 scales comfortably for growing small and medium businesses as well as larger enterprises. Teams can host meetings from desktop, mobile, or web browsers using the free Wave app, with support for up to 15 public rooms and 200 total participants. The Telecom Spot Take For organizations that still use analog phones or need reliable PSTN connectivity alongside full IP capabilities, the UCM6304 offers a practical sweet spot. The hybrid port design with built-in lifeline support helps maintain service during power or network events — a key consideration for facilities managers. IT directors appreciate the native video collaboration tools, extensive call center features like ACD queues and skill-based routing, and the API for CRM or PMS integrations. The rack-mountable chassis, redundant power inputs, and compatibility with Grandstream’s GDMS cloud management platform make it straightforward to deploy and maintain. It is especially well-suited for businesses that want strong on-premises security and a single platform that grows without forcing an immediate rip-and-replace of legacy equipment. Key Features 4 FXS + 4 FXO ports with lifeline capability — Directly connect analog telephones and PSTN lines for hybrid environments; ports stay active during power outages for business continuity. Up to 2000 users and 300 concurrent calls (200 SRTP) — Scales with your business while delivering clear voice quality and secure encrypted calls. Built-in video & web meetings platform — Host unlimited rooms (up to 15 public) with a combined 200 participants and up to 9 video feeds per room — accessible via Wave app on desktop, mobile, and browsers with no extra licenses required. Three Gigabit Ethernet ports with PoE+ and NAT router — Flexible deployment in switched, routed, or dual mode; power compatible Grandstream phones directly from the PBX. ZeroConfig provisioning & GDMS compatibility — Rapidly deploy Grandstream SIP endpoints with almost zero manual configuration; manage the entire system on-site or through Grandstream’s cloud platform. Advanced security built in — Secure boot, unique device certificate, random default passwords, SRTP/TLS encryption, 802.1X, and automated NAT firewall traversal for safe remote access. Full-featured call center & collaboration tools — ACD queues, skill-based routing, customizable IVR (up to 64 layers), call recording, voicemail-to-email, paging/intercom, and more. Free Wave app across platforms — Desktop (Windows/Mac), mobile (iOS/Android), and web browsers let users make calls, join meetings, chat, and share files with anyone registered to the UCM. High-availability ready — Supports hot-standby redundancy for mission-critical deployments. Asterisk 16 foundation with rich codecs — Full-band Opus voice and H.265/H.264 video support plus excellent jitter resilience up to 50% packet loss for reliable performance on varied networks. Technical Specifications Hardware Analog FXS Ports 4 RJ11 (lifeline capable) PSTN FXO Ports 4 RJ11 (lifeline capable) Network Interfaces 3× self-adaptive Gigabit RJ45 ports (switched/routed/dual mode) with PoE+ Peripheral Ports 2× USB 3.0, 1× SD card slot Display 128×32 dot matrix LCD with navigation buttons Power Dual DC 12V inputs (100–240V AC adapter, 2A output) Dimensions 485 × 187.2 × 46.2 mm (rack-mount & desktop) Weight 2.49 kg (unit) Mounting Rack mount & desktop Capacity & Performance Maximum Users 2,000 Concurrent Calls (G.711) 300 Max Concurrent SRTP Calls (G.711) 200 Meeting Rooms Unlimited (up to 15 simultaneous public rooms) Max Meeting Participants 200 total across rooms Video Feeds per Room Up to 9 Software & Features Telephony OS: Asterisk version 16 Voice Codecs: Opus (full-band), G.711, G.722, G.729A/B, iLBC, GSM + T.38 fax Video Codecs: H.265, H.264, H.263, VP8 Security: SRTP, TLS, HTTPS, SSH, 802.1X, ZRTP, secure boot, unique certificate Networking: NAT router, automated firewall traversal, IPv6, OpenVPN Provisioning: ZeroConfig, AES-encrypted XML, GDMS cloud management Call Features: Full suite including ACD queues, IVR (64 layers), call recording, voicemail-to-email, ring groups, paging/intercom, DISA, SCA/BLF, and more API: Full API available for third-party CRM/PMS integrations Multi-language support for web UI and voice prompts Comparison at a Glance (UCM6300 Series) Model FXS/FXO Ports Max Users Concurrent Calls (G.711) Meeting Rooms / Max Participants UCM6302 2 / 2 1,000 150 8 / 150 UCM6304 4 / 4 2,000 300 15 / 200 UCM6308 8 / 8 3,000 450 25 / 300 The UCM6304 offers the ideal balance for most growing businesses that need more analog connectivity and capacity than the UCM6302 but do not yet require the full scale of the UCM6308. FAQ How many users and calls does the UCM6304 support? Up to 2,000 users and 300 concurrent calls using the G.711 codec (200 when using SRTP encryption). Can I keep my existing analog phones and PSTN lines? Yes. The UCM6304 includes 4 FXS ports for analog telephones and 4 FXO ports for PSTN trunks. Every port has lifeline capability so calls can continue during power outages. Does it include video conferencing? Yes. The built-in meetings platform supports up to 15 public rooms simultaneously, a total of 200 participants across all rooms, and up to 9 video feeds per room. Users join from the free Wave app on desktop, mobile, or web browsers. How secure is the UCM6304? It uses secure boot, a unique security certificate, random default passwords, SRTP/TLS media and signaling encryption, 802.1X network access control, and automated NAT traversal. It also works seamlessly with Grandstream Device Management System (GDMS) for centralized secure management. Is it easy to set up with Grandstream phones? Absolutely. ZeroConfig technology auto-discovers and provisions Grandstream SIP endpoints with almost no manual work required. Backed by Grandstream’s proven hardware platform and designed for reliable day-to-day operation in real business environments.

The Grandstream UCM6304 is a rack-mountable hybrid IP PBX that brings together voice, video, conferencing, and collaboration tools in one secure, easy-to-manage appliance. It features 4 FXS ports for connecting analog phones and 4 FXO ports for PSTN lines, giving businesses a smooth path to modern communications while protecting existing investments and ensuring uptime with lifeline capability on every port.

With capacity for up to 2000 users and 300 concurrent calls (200 secure SRTP calls), plus a powerful built-in meetings platform, the UCM6304 scales comfortably for growing small and medium businesses as well as larger enterprises. Teams can host meetings from desktop, mobile, or web browsers using the free Wave app, with support for up to 15 public rooms and 200 total participants.

The Telecom Spot Take

For organizations that still use analog phones or need reliable PSTN connectivity alongside full IP capabilities, the UCM6304 offers a practical sweet spot. The hybrid port design with built-in lifeline support helps maintain service during power or network events — a key consideration for facilities managers. IT directors appreciate the native video collaboration tools, extensive call center features like ACD queues and skill-based routing, and the API for CRM or PMS integrations. The rack-mountable chassis, redundant power inputs, and compatibility with Grandstream’s GDMS cloud management platform make it straightforward to deploy and maintain. It is especially well-suited for businesses that want strong on-premises security and a single platform that grows without forcing an immediate rip-and-replace of legacy equipment.

Key Features

• 4 FXS + 4 FXO ports with lifeline capability — Directly connect analog telephones and PSTN lines for hybrid environments; ports stay active during power outages for business continuity.
• Up to 2000 users and 300 concurrent calls (200 SRTP) — Scales with your business while delivering clear voice quality and secure encrypted calls.
• Built-in video & web meetings platform — Host unlimited rooms (up to 15 public) with a combined 200 participants and up to 9 video feeds per room — accessible via Wave app on desktop, mobile, and browsers with no extra licenses required.
• Three Gigabit Ethernet ports with PoE+ and NAT router — Flexible deployment in switched, routed, or dual mode; power compatible Grandstream phones directly from the PBX.
• ZeroConfig provisioning & GDMS compatibility — Rapidly deploy Grandstream SIP endpoints with almost zero manual configuration; manage the entire system on-site or through Grandstream’s cloud platform.
• Advanced security built in — Secure boot, unique device certificate, random default passwords, SRTP/TLS encryption, 802.1X, and automated NAT firewall traversal for safe remote access.
• Full-featured call center & collaboration tools — ACD queues, skill-based routing, customizable IVR (up to 64 layers), call recording, voicemail-to-email, paging/intercom, and more.
• Free Wave app across platforms — Desktop (Windows/Mac), mobile (iOS/Android), and web browsers let users make calls, join meetings, chat, and share files with anyone registered to the UCM.
• High-availability ready — Supports hot-standby redundancy for mission-critical deployments.
• Asterisk 16 foundation with rich codecs — Full-band Opus voice and H.265/H.264 video support plus excellent jitter resilience up to 50% packet loss for reliable performance on varied networks.

Technical SpecificationsHardwareAnalog FXS Ports4 RJ11 (lifeline capable)PSTN FXO Ports4 RJ11 (lifeline capable)Network Interfaces3× self-adaptive Gigabit RJ45 ports (switched/routed/dual mode) with PoE+Peripheral Ports2× USB 3.0, 1× SD card slotDisplay128×32 dot matrix LCD with navigation buttonsPowerDual DC 12V inputs (100–240V AC adapter, 2A output)Dimensions485 × 187.2 × 46.2 mm (rack-mount & desktop)Weight2.49 kg (unit)MountingRack mount & desktopCapacity & PerformanceMaximum Users2,000Concurrent Calls (G.711)300Max Concurrent SRTP Calls (G.711)200Meeting RoomsUnlimited (up to 15 simultaneous public rooms)Max Meeting Participants200 total across roomsVideo Feeds per RoomUp to 9Software & Features

• Telephony OS: Asterisk version 16
• Voice Codecs: Opus (full-band), G.711, G.722, G.729A/B, iLBC, GSM + T.38 fax
• Video Codecs: H.265, H.264, H.263, VP8
• Security: SRTP, TLS, HTTPS, SSH, 802.1X, ZRTP, secure boot, unique certificate
• Networking: NAT router, automated firewall traversal, IPv6, OpenVPN
• Provisioning: ZeroConfig, AES-encrypted XML, GDMS cloud management
• Call Features: Full suite including ACD queues, IVR (64 layers), call recording, voicemail-to-email, ring groups, paging/intercom, DISA, SCA/BLF, and more
• API: Full API available for third-party CRM/PMS integrations
• Multi-language support for web UI and voice prompts

Comparison at a Glance (UCM6300 Series)ModelFXS/FXO PortsMax UsersConcurrent Calls (G.711)Meeting Rooms / Max ParticipantsUCM63022 / 21,0001508 / 150UCM63044 / 42,00030015 / 200UCM63088 / 83,00045025 / 300

The UCM6304 offers the ideal balance for most growing businesses that need more analog connectivity and capacity than the UCM6302 but do not yet require the full scale of the UCM6308.

FAQHow many users and calls does the UCM6304 support?

Up to 2,000 users and 300 concurrent calls using the G.711 codec (200 when using SRTP encryption).

Can I keep my existing analog phones and PSTN lines?

Yes. The UCM6304 includes 4 FXS ports for analog telephones and 4 FXO ports for PSTN trunks. Every port has lifeline capability so calls can continue during power outages.

Does it include video conferencing?

Yes. The built-in meetings platform supports up to 15 public rooms simultaneously, a total of 200 participants across all rooms, and up to 9 video feeds per room. Users join from the free Wave app on desktop, mobile, or web browsers.

How secure is the UCM6304?

It uses secure boot, a unique security certificate, random default passwords, SRTP/TLS media and signaling encryption, 802.1X network access control, and automated NAT traversal. It also works seamlessly with Grandstream Device Management System (GDMS) for centralized secure management.

Is it easy to set up with Grandstream phones?

Absolutely. ZeroConfig technology auto-discovers and provisions Grandstream SIP endpoints with almost no manual work required.

Backed by Grandstream’s proven hardware platform and designed for reliable day-to-day operation in real business environments.

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