DiameterGateway.com “As LTE, 4G and IMS network deployments press ahead in conjunction with existing GSM, 3G and PSTN infrastructure, access to legacy SS7 and M3UA Sigtran based networks will be vital” The resemblance between Diameter and SS7 is that both are signaling protocols. Diameter mosly used for Authentication, Authorization and Accounting in 3GPP latest releases. Diameter typically provides the access control and accounting based services on top of an IP network. SS7 mostly focuses on call control and service management mostly within traditional PSTN and GSM networks. SS7 signalling can be implemented on top of IP network in order to support the nodes that do not have diameter functionality using a signalling gateway which function the interworking between different layers of SS7 and OSI. Diameter protocol provides communication between network nodes with enhanced access control on top of IP network, while SS7 protocol defines all layers of OSI with support for legacy TDM (networks. As per the diameter, the network node can act as either a client or a server for two different connections, while in SS7 each node is given a separate signalling point code to identify them within a network. SS7 SS7 Signaling was developed to call management and service signalling requirements of the digital networks based on the full duplex channels. In SS7 network structure, the nodes are called signalling points, while the connection between those nodes is called signalling links. In SS7 networks Signalling Transfer Points (STPs) are introduced to relay and route the messages between signalling points. SS7 has point to point architecture with one to one physical correspondence between two signalling points. SS7 structure initially developed to have compatibility with OSI model as well. Message Transfer Part (MTP) 1 to 3 used in SS7 are similar to OSI first 3 layers, while SCCP (Signalling Connection Control Protocol) in SS7 protocol provides the connectionless or connection oriented communication between signalling points. Diameter versus SS7