Interface Converters is also called protocol converters. The interface converters are used to transform signals from one kind of network to the other kind of network, typical types include E1 to Ethernet, V35 to Ethernet and E1 to V35. Protocol converters are mainly used for SDH networks, they provide a common transport infrastructure which is capable of delivering diverse services to customers. In the future, SDH will support broadband ATM applications as well as today's voice and data services. In addition, there is an increasing demand to support broadcast television services.