OC3   Short for Optical Carrier. OCx lines are used by large corporations or providers as backbone lines to the Internet. The table below shows the speeds for common OC levels. OC = Speed OC-1 = 51.85 Mbps OC-3 = 155.52 Mbps OC-12 = 622.08 Mbps OC-24 = 1.244 Gbps OC-48 = 2.488 Gbps OC-192 = 9.952 Gbps OC-255 = 13.21 Gbps