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| Typical System Components in a Next Generation Communications Platform | |
| Component | Function |
| Media Server | Terminates IP and/or circuit switched traffic via multi-interface design and is responsible for trunking and call control |
| Application Server | Modular, application building blocks; server generates dynamic VoiceXML pages; external interface via Web Application Server configuration |
| Systems Management Unit (SMU) |
A management portal that enables service providers to provision and maintain subscriber accounts and manage network elements from a centralized web interface |
| Centralized Message Store | Stores voice messages, subscriber records, and manages specific application functions including notification |
| Signaling Gateway | A consolidated SS7 interface |
Media Server
The media server terminates IP and circuit-switched traffic and is responsible for call set up and control within the platform architecture. The media server processes input from the user in either voice or DTMF format (much like a web client gathers keyboard and mouse click input from a user). It then presents the content back to the user in voice form (similar in principle to graphic and text display back to the user on a PC client). This client/server methodology is important in the platform architecture in that it enables rapid creation of new applications and quick utilization of content available on the World Wide Web.
The media server processes incoming calls via requests to the application server using HTTP. A load balancer directs traffic arriving at the multi-function media server to one of a plurality of Application Servers (Figure #2). This functionality ensures that traffic is allocated evenly between active servers. The multi-function media server works as the VoiceXML client on behalf of the end user in much the same manner as a client like Netscape works on behalf of an HTML user on a PC. A VoiceXML or CCXML browser residing on a multi-function media server interprets the VoiceXML documents for presentation to users.
VoiceXML is a standards-based scripting language for developing voice-enabled software applications. This means that developers use and leverage Web-based (HTML) development expertise in developing speech-based telephony applications.
The media server interfaces with the PSTN, Automatic Speech Recognition and Text-to-Speech servers (ASR, TTS) and provides VoIP (SIP, H.323) support. VoIP is supported through G.711 and G.723 voice encoding. The media server contains a built-in abstraction layer for interface with multiple speech vendors – eliminating dependency on a single ASR or TTS vendor.
The media server is a COTS carrier-grade server. Telephony interface and resource boards for telephony-specific applications can also be added. A fax card added to this server manages fax termination. The fax message store is a “soft” component within the media server. The media server has built in code and echo cancellation. Call Detail Records (CDRs), used by service providers for billing purposes, are provided as well as SNMP alarming, logging, and transaction detail records. The media server connects to the other components in the next generation platform through Ethernet connections. It is NEBS compliant and supports N+1 fail over redundancy schemes and load sharing configurations. Each media server is equipped with I/O interfaces, cooling systems, and is horizontally and vertically scalable.
Figure 2. How the media server inter-works within the next generation communications platform
Application Server
The modular design of the next generation communications platform makes it easy to deploy enhanced services such as voice dialing and voice navigation, unified communications solutions, multimedia messaging services, and presence & availability management applications. Adding applications to the platform is accomplished via the addition of standard application servers to the common platform.
The application server generates application documents (VoiceXML pages) in response to requests from the media server via the internal Ethernet network. The application server leverages a web application infrastructure to interface with back-end data stores (messages stores, user profile databases, content servers) to generate documents (e.g., VoiceXML pages). The overall web application infrastructure separates the core service logic (i.e., providing the business logic) from the presentation details (VoiceXML, CCXML, SALT, XHTML, WML) to provide a more extensible application architecture.
The application server utilizes Java 2 Enterprise Edition (J2EE) environment and Java Server Pages (JSP) to create the dynamic VoiceXML pages for the multi-function media server. Combining these technologies enables rapid incorporation of Speech Application Language Tags (SALT) to provide interoperability (multimodal) between applications like WAP, HTML, XHTML and voice – allowing the end user to simultaneously input data via voice command and receive presentation via WAP or HTML.
To create an environment for easy application development the application server supports Template+ JSPs. Applications are implemented in JSPs using an API for access to messaging functions. These JSPs are readily modifiable making changes in application behavior and creation of new applications very easy.
Each Application Server provides its own I/O interfaces and cooling. This common off-the-shelf server is vertically scalable and is used to deliver applications to the end user. As with all platform components, SNMP alarming, logging, and transaction detail records are generated.
Centralized Message Store
The next generation communications platform uses a centralized message store called an NGMS. The NGMS stores voice/audio messages, subscriber records, and manages certain application functions such as notification schedules. The NGMS is designed with fully redundant components and utilizes reflective memory and Redundant Array of Independent Disks (RAID) technology for fault tolerance, immediate fail over and recovery. This ensures five 9’s availability for associated hardware and software components. Essential disk drive and RAID controller components are also “hot swappable” eliminating the need to power down the system for replacements.
With the NGMS, performance is optimized for the unique characteristics of voice messaging, eliminating the performance degrading, unnecessary e-mail-centric database functionality that comes with the searching and sorting of e-mail stores.
System Management Unit (SMU)
The SMU provides a centralized point for service providers to manage all network elements, providing remote access, maintenance, and backup functionality. The SMU provides a single interface for provisioning, alarming, reports, and subscriber migration. The SMU integrates and customizes systems with new elements and applications, and provides operational support and network management functions for carriers experiencing swiftly growing networks and exploding traffic volumes. Core features of the element management component include:
- Element Auto-Discovery – when service providers add new network elements, the SMU automatically recognizes them and includes the new elements in the graphical network map.
- Graphical Network Map – a network/cluster map and map editor provides a snapshot of the entire network or cluster and facilitates quick problem identification and resolution.
- Time Synchronization – a central time source ensures all network components maintain a uniform time reference across the entire messaging network – important for any distributed architecture.
- Centralized network logging – logging for the entire messaging network is centralized on the SMU.
| Element Management Category | Function Supported |
| System Configuration and Setup |
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| Network Management and System Monitoring |
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| Statistics and Reporting |
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| Fault Management and Alarms |
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| Subscriber and Mailbox Admin |
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| Computer Interface for Centralized Provisioning |
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| CDR Capture for Billing |
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Signaling Gateway Function
The Signaling Gateway Function offers a consolidated signaling interface creating a single virtual SS7signaling point for the next generation communications platform. SS7 provides the extra horsepower networks need, whether large or small. A sigtran interface (IETF SS7 telephony signaling over IP) to the multi-function media server as well as IP Proxy functions are supported via SGF. Consolidating SS7 provides the benefits of reduced point codes and easier maintenance.
The availability of point codes is typically limited. The consolidation of signaling links eases the pressure on these resources or eliminates the need for additional point codes altogether. In this way, the SGF provides immediate network simplification and cost savings. The SGF presents the appearance of a single identity to the SS7 network via the single “virtual” point code of the messaging network and recognizes and processes messages in a transparent manner. The SGF can potentially reduce the maximum number of point codes needed in some cases from 50 to only four.
The SGF server supports N+1 fail over redundancy schemes and load sharing configurations and is built on an Intel server. A minimum of two SGFs is recommended for load sharing and redundancy purposes for increased availability. As with all platform components, SNMP alarming, logging, and transaction detail records are generated. Features, advantages and benefits of the SGF include:
- Allows multiple Media Servers to share signaling links and Point Codes (PC) providing significant cost savings
- Provides concentrated SS7 signaling links
- Can provide one trunk group across multiple multi-function media servers
- SGF requires less SS7 links resulting in reduced monthly connection fees
