Figure 7-4: Leased Line Speeds, Continued North American Digital Hierarchy Line peed Typical Transmission Medium 1.544 Mbps 2-Pair Data-Grade UTP T3 44.736 Mbps Optical Fiber The jump from T 1 to T3 speeds is extremely large Few firms need T3 speeds, and they only need these speeds for some of their leased lines Some carriers offer fractional T3 lines to bridge the T1-T3 gap T3 lines and all faster leased lines use optical fiber 7-107-10 Figure 7-4: Leased Line Speeds, Continued Line Speed Typical Transmission Medium North American Digital Hierarchy T3 44.736 Mbps Optical Fiber The jump from T1 to T3 speeds is extremely large. Few firms need T3 speeds, and they only need these speeds for some of their leased lines. Some carriers offer fractional T3 lines to bridge the T1-T3 gap. T3 lines and all faster leased lines use optical fiber. T1 1.544 Mbps 2-Pair Data-Grade UTP