Central Grandstream UCM6304A Central Grandstream IP PBX UCM6304A is specially designed to meet the needs of business organizations and companies that want to control their communications. It supports multiple features such as voice calls, video calls, and video conferencing. It allows employees to communicate via computers, mobile phones, and video conferencing devices. It also helps Businesses build powerful and scalable communication and collaboration solutions, featuring a sleek, streamlined look, plus support for 1,000 users and up to 150 concurrent calls. Central Grandstream UCM6304A IP-PBX Features 4 RJ11 Ports FXS, 4 RJ11 Ports FXO - 1000 Users, 150 Concurrent Calls - 2*USB 3.0, 1*SD card interface - 3 Gigabit Ports with PoE+ - 7 meeting rooms and up to 120 parties