Grandstream GS-UCM6104 4 Port Innovative IP PBX Appliance - Black Supports up to 500 SIP endpoint registrations, up to 60 concurrent calls and up to 32 conference attendees Integrated 4 PSTN trunk FXO ports, 2 analog telephone FXS ports with lifeline capability and up to 50 SIP trunk accounts Gigabit network ports with integrates PoE, USB, SD card 512 MB DDR Ram, 4GB NAND flash Comprehensive security protection using SRTP, TLS with hardware encryption accelerator