Cisco offers a complete line of accessories and spares for its high quality network products to make it easier to adjust them to your specific needs.Offered is SS7 4 link system. SS7 is characterized by high-speed packet switching and out-of-band signaling, using Service Switching (SSPs), Signal Transfer Points (STPs), and Service Control Points (SCPs) (collectively referred to as signaling points, or SS7 nodes). Out-of-band signaling is signaling that does not take place over the same path as the data transfer (or conversation) - a separate digital channel is created (called a signaling link), where messages are exchanged between network elements at 56 or 64 kilobit per second.