Softswitch SIP Proxy Server Call Manager IP Telephony Router Tablet PC IP PBX Class 5 Switch Class 4 Switch PBX Access Gateway Broadband Router Voice Gateway Bridge Server Data Class 4/5 Switch Switch Voice- Enabled IP IP Network SS7Data Network Signaling Gateway Universal Media Gateway Analog Telephone IP Telephone Digital Telephone IP Telephone

Figure 7-1 Softswitch Architecture Components Signaling Gateway Feature Server Softswitch Universal Media Gateway SGCP SIP MGCP MGCP (Media Gateway Control Protocol) SGCP (Simple Gateway Control Protocol) call agent SIP ( Session Initiation Protocol)

Figure 7-3 PC to PC and PC to phone IP Network Voice Gateway Class 4 Switch Telephone PC

Figure 7-4 IP phone on an IP network IP Telephone IP Network Data Softswitch Server

Figure 7-5 SOHO gateways in a VOIP network IP Network Softswitch Data Server Telephone

Figure 7-6 Enterprise gateways on a VoIP network IP Network Voice Gateway Server Data Softswitch PBX Digital Telephone Voice Gateway PBX Digital Telephone

Figure 7-7 VoIP gateways in carrier-grade applications IP Network Voice Gateway Server Data Softswitch Digital Telephone Voice Gateway Digital Telephone Class 4/5 Switch

Figure 7-8 IP PBX also known as soft PBX IP Network IP PBX IP Telephone

Figure 7-9 IP Centrex using a Class 5 switch and GR-303 interface IP Network Voice Gateway Telephone Class 5 Switch GR303 Gateway

Figure 7-10 IP Centrex with Softswitch IP Network Voice Gateway Server Data Softswitch PBX Digital Telephone Voice Gateway PBX Digital Telephone

Figure 7-11 Architecture of Class 4 switches with VoIP gateways IP Network Voice Gateway Server Data Softswitch Telephone Voice Gateway Telephone Class 4 Switch Class 5 Switch

Figure 7-12 Class 4 replacement Softswitch solution Note the absence of Class 4 TDM switches IP Network Softswitch Data Server Voice Gateway Class 5 Switch Telephone

Figure 7-13 Class 5 replacement Softswitch solution IP Network Voice Gateway Server Data Softswitch Telephone Voice Gateway Telephone

Figure 7-14 Legacy networks: separate voice and data networks Class 5 Switch Telephone Data Network voice Network SS7 Class 4 Switch Class 5 Switch Class 4 Switch Telephone

Figure 7-15 Converging networks: a mix of circuit- and packet-switched networks and technologies Telephone IP Network Class 4 Switch Class 5 Switch Universal Media Gateway Softswitch SS7 Server Class 5 Switch Telephone

Figure 7-16 A converged network is one network for voice and data. IP Network Server Softswitch IP Telephone Telephone Enterprise Media Gateway SOHO Media Gateway Carrier Grade Media Gateway IP

Figure 7-17 Local Access Softswitch-Based Architecture IP Network SS7 Class 5 Switch Server Digital Telephone Telephone Trunking Gateway PBX Internet 911 Services Operating Services APP Server Agg Router IAD Customer Premise Feature Servers (CLASS, Unified Messaging) Call Agent

Signaling Gateway Feature Server Softswitch Universal Media Gateway SGCP SIP MGCP MGCP (Media Gateway Control Protocol) SGCP (Simple Gateway Control Protocol) call agent SIP ( Session Initiation Protocol)

Developing Softswitches As the new public network comes to fruition, the end is in sight for the traditional proprietary PSTN circuit switch. The functionality of the traditional circuit switch has been delegated to separate nodes including the softswitch, media gateway, signaling server, and application server. Defined by the International Softswitch Consortium as a device that has call control, signaling, and feature creation/delivery capabilities, the softswitch forms the foundation of the new public network infrastructure. However, in an environment of resource constraints, TEMs (telecom equipment manufacturers) developing these softswitch applications are facing increasing demands on time-to- market and cost. The business problem for TEMs is how to focus on developing robust and reliable softswitch applications while also addressing the complex and work-intensive areas of hardware design, high availability, integration, and management at the platform level.