The KX-TDA50G control unit is initially configured with 4 Super HybridExtension Ports and 4 Loop Start CO ports (1 LCOT card), PowerSupply, RS-232 port, USB port, MOH port, Paging port and an SD card.The system is expandable to 12 COs and 24 Extension ports.Features • Multi-Cell Wireless • VOIP Gateway with QSIG (Enhanced System Networking) • PC-Based Programming • Digital Extra Device Port DXDP • Automatic Route Selection (ARS) • Toll Restriction • Built-in Caller ID Name & Number to (DPT, APT & SLT) for first 4 CO lines • In Skin Voice Mail Card and Voice Mail Integration • Uniform Call Distribution (UCD) • Direct Inward System Access (DISA) • Supports SIP Trunking