Packet Transport Networks (PTN) combine the advantages of packet technology and Synchronous Digital Hierarchy (SDH) technology. Taking the packet switch as its core, PTN has a high statistical multiplexing ability, which allows it to become a more efficient packet transfer service. Its strong Operation Administration and Maintenance (OAM)—similar to SDH and carrier-class security protection services—ensures efficient mobile backhaul business management and transmission quality. MPLS Transport Profile (MPLS-TP) packet transport network eliminates connectionless features, such as Penultimate Hop Popping (PHP), label merge and Equal-cost multi-path (ECMP), and is enhanced in terms of OAM, protection, and synchronization. This is ideally suited for carrying IP-based mobile backhaul services and key account services. PTN, original Multi-Service Transport Platform (MSTP), Metro Ethernet, and IP over Wave Division Multiplexing (WDM)/Optical Transport Network (OTN) of organic complexes, contribute to an "all IP" era of telecommunications services.