18. SIP calling setup between Quadro’s Internet PC / Soft phone Quadro 4X Quadro 2X IP Phones SIP PSTN Lines Shelcomm Voxitas Broad voice Ethernet Switch SIP IP Phones IP PSTN Lines Voxitas Broad voice PC / Soft phone India Site SIP Remote office US Ethernet Switch IP Phones Schaumburg Site PC / Soft phone IP Phones Ethernet Switch Quadro 2X Voxitas , Cbeyond PC / Soft phone IIT Site SIP Quadro 2X