The Grandstream UCM6304 is an easy to manage device that does not require licensing fees and can support up to 2000 users and up to 300 concurrent calls. It features advanced technology including three Gigabit auto-sensing RJ45 network ports with integrated PoE+ and support for a NAT router. This enterprise-grade IP PBX can be integrated with third-party CRMs and PMS allowing for custom integrations. 
The Grandstream UCM6300 Series of IP PBX's have been designed with business of all sizes in mind, creating a unified communications solution that is robust and scalable. Moreover, the UCM6300 Series can be managed through the Grandstream Device Management System (GDMS) allowing for cloud-based setup, easy management and monitoring.
Grandstream UCM6304 IP PBX Features and Specifications
Enterprise-Grade Unified Communication Solution
IP PBXs allows businesses of all sizes to build powerful and scalable unified communication solutions in an easy-to-manage fashion with no licensing fees
Analog Telephone FXS Ports: 4 RJ11 Port
PSTN Line FXO Ports: 4 RJ11 Port
Users: 2000
Concurrent calls: 300
Max concurrent SRTP calls: 200
Video Conference: Up to 30
Voice Conference: Up to 120
Three self-adaptive Gigabit ports (switched, routed or dual card mode) with PoE+
1USB 2.0, 1USB 3.0, 1SD card interface
320x240 color LCD with touch screen for Shortcut Keys and Scroll Bar