Due to the competitions between the telecommunication service providers, the required capacities are increasing all the time. It is important for these providers to develop a network that can transfer more data bytes from one place to another. In addition, the mobile traffic and the internet services need more capacities in the telecommunication networks. Therefore, it is mandatory for the networks to handle large amounts of data in a fast and a reliable way. Of course, one possibility would be Ethernet traffic, but in cellular transmission networks there are a strict requirement for delay, data loss and synchronization and this is why the Ethernet is not yet supported.The Synchronous Digital Hierarchy (SDH) is one answer for increasing the network data traffic. For example, if we need to transfer 63 × 2.048 Mb/s (E1) signals from one place to another a huge amount of wires will be needed, on the other hand the SDH needs only two fibers to do the same operation. Many vendors have a product called STM1 multiplexer and its functionality to add and drop 63 × 2.048 Mbit/s into 155.52 Mbit/s (STM-1). The bit rates of the basic signals in the SDH are derived from the same clock source, which means that the SDH is completely synchronous transmission system. SDH has many different hierarchy levels starting from 155.52 Mbit/s to 10 Gbit/s and the STM-1 with a bit rate of 155.52 Mbit/s is the basic module of the SDH system. The SDH signal is terminated to E1 (2.048 Mbit/s) signals by using terminal multiplexer.Before the SDH multiplexer operates in the telecommunication market, there is a huge amount of work to put the requirements specifications, by studying the reality of the market needs. Many chip manufacturers have SDH chips in their product catalog, so one has to make a decision which manufacturer's chip to use. In addition, one must decide how to handle overhead bytes and how to implement all this in network manager software. After all these decisions, we have a huge amount of data and the last thing to do is to decide which features are implemented and which are not. Because of time-to-market pressures, the implementation has to be phased and the first phase must contain only the necessary functionality and nothing more to reduce the development time to minimum.The Synchronous Digital Hierarchy (SDH) multiplexers form the core part of the backbone telecommunication networks, and the effective design, reliability analysis and training are essential to managing SDH network effectively. Today and shortly, the demands to transfer a tremendous mass of data among the various applications in many fields inside the country become an exclusive responsibility particularly with the significant developments of the clouding policies in the different forms such the data centers and the implementations of many smart applications of the 5G in the various areas of the information technologies. The current design of the core communication network consists of 3 independent zones, the 1'st zone is layer 1 and layer 2 which recognized as the physical layer of the core optical network such Optical Transport Network (OTN), the 2'nd band is layer 3 which viewed as IP core network, and the last zone is the access and the application layers such 4G network. The challenge in the current communication model is no associations among these 3 zones of the communication network to optimize the capacities and the needed resources which are required to carry the data among any of them. Now the optical transport network (OTN) represents the critical point of carrying a tremendous amount of data for the mobile network such 4G between the different sites.