Asterisk VA-20 VoiceArt IP PBX system has 1 GB RAM, 1.2 GHz 64-bit quad-core ARMv8 processor, micro USB power, extension 20, concurrent call 15, USB power / backup from power bank, music on hold, caller display, HD sound, conference call, individual call report, welcome voice IVR, call forward / transfer, 1 year warranty.