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Voice and data convergence. It seems like everyone’s been talking about for ages now, but what exactly is it all about? More importantly, how can you benefit from it?

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By  Alex Marklew Published  December 11, 2000

Voice and data convergence. It seems like everyone’s been talking about for ages now, but what exactly is it all about? More importantly, how can you benefit from it?

Andrew A. Beutmueller from Siemens is convinced that VDC is the way forward. Here he explains the ideas behind the technology, and reveals what it can do for you.

According to Gartner Group, more than 60 million employees worldwide do not work in a traditional office setting. By 2002, that number will jump to 108 million. Siemens’ Mobile Business program gives these workers, and many others, the freedom to leave their twentieth-century offices behind.

Mobile Business is more than just mobile phones and wireless communications. It’s a whole new way of communicating that is all about freedom, accessibility and convenience.

Mobile Business offers people the freedom to work and roam without being tied to one particular place. Mobility allows people to work more efficiently–whether traveling, at home or in the office–with constant access to tools, files, colleagues and clients.

Mobile Business frees people from their desk chairs, but gives them access to their desktops 24 hours a day, seven days a week.

Mobile Business-enabled professionals are accessible through any kind of network–wireless or wireline. Clients, bosses and co-workers can always locate the mobile professional armed with a cell phone or notebook computer and anchored by a high-speed, dependable, secure telecommunications network.
Mobile Business affords users the ability to access information over any kind of device. Mobile services, applications and devices are evolving to fit users’ on-the-go, busy lifestyles.

People can transmit data and conduct transactions such as stock purchases and airline reservations through their mobile phones, television sets, electronic organizers and personal computers (PCs).

Mobile Business’ benefits do not extend only to individuals. By implementing Mobile Business, enterprises become more efficient, too. Mobile enterprises can manage their human resources more effectively.

They can set up broadband services to “virtually network” teams so they can communicate in real time, even though they’re around the corner or across the globe.

They can make their offices portable by enabling workers to access all applications, even high-bandwidth multimedia applications, from any location.

Mobile enterprises can manage inter-organizational relationships and improve scheduling and distribution systems to streamline their supply and value chains.

For instance, they can reduce unneeded in-person meetings and other processes that don’t add value to their core offerings. Or, they can set up Virtual Private Networks (VPNs) to interact as one large group of companies.

Most importantly, Mobile Business will enable companies to develop completely new business models, including location-based electronic commerce, where local businesses advertise special offers as mobile users enter their neighborhoods.

IP-convergence is fueling the mobile Internet fire. Packet-switched technology has inherent advantages that cannot be overlooked—in particular, bandwidth flexibility.

Data networks also are evolving to serve new applications and new end-user markets. They are evolving to multi-service, real-time and non-real- time networks, drawing advantages through the economies of scale, integrated support of IP and the openness for future change.

No matter what underlying network technology is used for transport, the money is in voice and in voice-data value-added services. Carriers combining the economy of scale and flexibility of the data network with voice revenues will be perfectly positioned to benefit from the two worlds of voice and data.

The customers are there, but how does a carrier cash in on this popularity?

To enter the lucrative voice business, the data network carrier needs to compete with the standards established by the Public-Switched Telephone Network (PSTN), which means provisioning voice networking features, such as the basic call with quality of service (QoS) and reliability guarantee, full call-routing and charging capabilities, and the flexibility for interconnection to arbitrary legacy networks by means of powerful signaling capacities.

The key to voice success for a data network carrier lies in fast and cost-efficient deployment of a voice-enabled IP or ATM network, covering, at the very least, the core characteristics of today’s TDM networks.

The bulk of voice traffic currently originates in the PSTN. Recent developments in VoIP/ATM technologies, however, have made it possible to transport voice in real-time over data backbone networks, using IP and ATM technologies.

Therefore, such a VoIP/ATM trunking solution allows a data network carrier to address the PSTN and ISDN residential and enterprise user base without having to make initial investments in voice access solutions.

In addition, there is a trend in the customer premises arena to integrate voice and data services in the end-user’s terminal equipment, whether it be via IP phones, voice-enabled PCs (H.323 terminals), LAN-based PBXs or enterprise voice-IP gateways.

They all share one common characteristic: they create voice traffic natively in the form of VoIP/ATM and feed the traffic straight into the data network without intermediate gateways.

Moreover, the addressable user base for a data network carrier in this scenario is the worldwide community of Internet and online users. This user base easily can be approached by a data carrier that is undergoing tremendous growth.

Offering voice networking and user services on top of a data network infrastructure allows data carriers to successfully compete with established carriers. However, the data network provider ultimately has the methods at his disposal to overtake the competition, namely by taking advantage of the key benefits inherent to his network.

Future development of integrated services for voice, video and data therefore easily can be based on a common denominator. Multimedia capability and the common IP layer are the basis for value-added, unique end-user services.

Carrying voice and data over a packet-oriented network provides several advantages.

First, it provides a flexible, future-proof solution that can rapidly be adapted to changing environments, such as variations in data or voice traffic volumes.

Next, it offers economies of scale. VoIP/ATM will profit indirectly from the very large growth rates in data networking technologies. Voice traffic becomes one in a number of other media streams in an IP- or ATM network.

Third, such a network enables multimedia capability. The voice-enabled data network is not restricted to services based on narrowband 64Kbit/s transmission, so it offers far greater bandwidth flexibility for end-user services such as desktop video-conferencing.

Last, the voice-enabled data network widely supports the IP protocol as a general layer, on top of which lie enhanced services. Converged voice-data services such as IP-based VPNs or IP-enabled voice conferences are the way to move beyond traditional voice offerings.

For the voice-data carrier, the situation is ideal: The open multimedia network provides the basis, and there are ample IP application developers available worldwide, plus a customer base receptive to new ideas.

To get the best from data and voice networks, carriers need wire-speed, cost-efficient mediation devices at the junction points of networks, controlled by centralized intelligence of a powerful call and feature server. Telecommunication and data networks today are still separate.

Packet-based data networks, especially the Internet, provide cost-efficient data transport and provision of many non real-time services such as e-mail, data VPN, file transfer and the World Wide Web.

On the other hand, the switched PSTN/ISDN network generally provides high-quality, real-time services such as telephony, video conferencing and many value-added features and services, including Centrex, voice VPN and Prepaid Card.

The simplest approach, of course, is to use the two networks in complementary fashion. But the question is how to bridge the technological gap between the two separate worlds?

A first approach is to interface with media gateways, which can establish a basic call and transport voice over packet networks.

This approach alone, however, cannot really compete with the high feature content provided by classical voice carriers and will not ensure the desired business volume expected when offering value-added voice and data converged services.

The missing link for a competitive transport of voice and provisioning of voice-data converged services is to introduce PSTN/ISDN network intelligence for packet networks.

This is achieved by a centralized Media Gateway Controller, applying this network intelligence to all media gateways at the edge of the network. All communication between the centralized controller and the network gateways is based on open and standardized protocols.

Media Gateways are the essential components to interconnect voice and data networks. They allow direct interfaces to the bearer trunks of the common, circuit-switched voice world and can convert the voice-band media streams into either ATM or IP packets.

These gateways simply work as plain mediation devices, unable to handle the network intelligence and thus to control voice or converged services.

This configuration is intentional: intelligent gateways would require a permanent update of user, service and network information, which ultimately leads to an almost unmanageable network and would pre-vent rapid introduction of new value added services.

A media gateway requires: direct Interfaces to PSTN/ISDN and IP/ATM world; real-time conversion of Voice over TDM to VoIP or VoATM (RTP); Media Gate Control Protocol (MGCP) for centralized service intelligence and decoupling of services from transport; high-density integration for smallest footprint and lowest power consumption.

Media Gateways are deployed along the data network border to act as the physical point of interconnection to traditional voice carrier networks. In contrast, only a few powerful Media Gateway Controllers are needed to provide the logical interfacing to the signaling of today’s voice world.

However, voice signaling is not only the simple set-up of a basic call. The key issue is the processing of hundreds of valuable and existing voice and IN services.

A Media Gateway Controller must therefore be able to understand this service logic and to support the quick translation into proper control information for every Media Gateway involved.

To allow communication between Media Gateway Controllers and Gateways, ITU-T, in cooperation with IETF, has standardized the open MGCP, which decouples the call and service control from the transport in order to achieve maximum flexibility for future networks.

This network architecture allows simplified and efficient network management, which is the basis for quick reaction to market demands and for new services and business opportunities.

Moreover, the centralized approach is the ideal platform for any kind of service provisioning by third-party applications that are interfacing via an open Application Programming Interface (API) to the Media Gateway Controller.

A Media Gateway Controller requires: Interfaces to all signaling protocols (ISUP, INAP, H.323/ SIP, MGCP/H.248, etc.); Decouple services from transport with MGCP/H.248; High-speed mediation between the different signaling systems of the voice world; Service intelligence for legacy voice and IN services; Centralized intelligence for fast introduction of new converged services; Open API for interfacing to third party service logic devices (e.g. e-commerce applications); includes Gatekeeper and RADIUS (AAA) Secure charging, performance measurement and network resource control.

In many countries it is more costly to interface to the PSTN/ISDN network via Primary Rate Access (PRA) than to interface carrier-like via SS7.

Therefore to lower interconnection costs, it is best to have Remote Access Server (RAS) connections to the PSTN controlled via MGCP with SS7 signaling being offered through a centralized Media Gateway Controller and Signaling Gateway.

A typical use of Media Gateway Controller and Media Gateways is virtual trunking. This application allows a straight conversion of circuit-oriented voice streams into packet data streams and vice versa, thus establishing ‘virtual trunks’ through any packet data network.

The Media Gateway Controller works as a signaling gateway and as a call feature server for perfect decoupling of services from transport.

Virtual trunking, in comparison to traditional circuit-switched trunking, benefits from the density, power and price of data networking and eliminates most of the trunk engineering required on a traditional TDM network.

Current network design already faces a huge challenge when simply interconnecting PSTN/ISDN subscribers with H.323/SIP multimedia users. It is almost impossible to provide transparency of existing voice features or new value-added converged services.

The main obstacle is the signaling and addressing inter-working. Using Media Gateways at the PSTN/ISDN border site and centralized Media Gateway Controllers for translating the signaling scheme from SS7 to H.323/SIP and vice versa provides an optimized network solution.

The result is the possibility of unlimited communication from phone to PC, PC to phone, or PC to PC. The Media Gateway Controller terminates the SS7 protocol at one end of the legacy voice world and acts on the other end as the end-point for communication with any H.323/SIP multimedia user.

The necessary address conversion from E.164 into IP and vice versa is supported by an attached gatekeeper functionality. Because of the H.323/SIP end-point functionality and the full SS7 and Intelligent Network (IN) capability of the Media Gateway Controller, most of the voice services will be available (e.g. Premium Rate, VPN, Centrex, Call Completion on Busy and No Reply, Calling Line Identification, etc).

Obviously, some voice services cannot be performed without support from the respective user applications. A good example is Call Transfer, where the application must allow the user interface to initiate the transfer of a call.

A network that can handle data, voice and converged services is no longer an engineer’s dream. It has become reality, thanks to the introduction of front-end Media Gateways, which can process and transform the full scope of desired network transport interfaces (TDM, ATM and IP).

In addition, the Media Gateway Controller handles signaling streams from PSTN/ISDN, IN, H.323/SIP user and Media Gateways while acting as a universal, open platform for provisioning a wide variety of voice-data converged services.

To provide carrier-class voice services, the underlying packet network must be able to ensure sufficient QoS. New IP switching and routing technologies (Multi-protocol label switching) provide a significant improvement in transport latency, jitter and packet loss compared to traditional IP networks.

In combination with large interfaces connected to DWDM optical units, this new IP switching and routing technology provides an excellent base for high quality packet telephony at reduced cost.

However, the best framework for carrier-class packet telephony and network reliability requirements is still found in ATM-switched networks. For direct interfacing of residential, SOHO and large corporate customers, a multi-service access unit offers integrated voice, xDSL and data services with direct connectivity to the packet network.

In particular, the incoming voice and dial-in modem traffic can be handled without diverting it to a traditional local exchange, thus providing an expansion of the data network right up to subscriber access.

Siemens’ new product family, SURPASS, paves the way to nearly unlimited voice communication among networks, protocols and standards. This product line efficiently bridges the gap between existing voice services and transport and the future-oriented architecture of data networking.

SURPASS builds a convincing business case for networking beyond limits with a rapid payback in the booming voice-data carrier markets. The whole product family is designed to operate natively in the packet world.

It is comprised of the following components: SURPASS hiG is a small footprint, high-density family of Media Gateways with VoIP, Voice over ATM (VoATM) and RAS functionality, designed for scalability to fit a range of small to large applications and to perform wire-speed conversion of legacy TDM to packet-oriented transport technologies.

HiG includes SURPASS hiG 500 RAS, VoIP SURPASS hiG 700 RAS, VoIP SURPASS hiG 1000 RAS, VoIP SURPASS hiG 2000 RAS, VoIP, VoATM.
SURPASS hiA is a new dimension of a multi-service access solution to handle emerging and legacy services on a common platform.

SURPASS hiA enables data carriers to greatly enhance their service portfolio while reducing the total cost of ownership. The modular flexible and scalable system supports ATM, FR, LL, xDSL, RAS and all variants of traditional POTS and ISDN interfaces.

SURPASS hiA is the best-in-class future-proof next-generation access system for both voice and data.

SURPASS hiQ is a modular, reliable, high-performance call and media controller, consisting of: hiQ 9400 Open Service Platform to provide an open API for rapid creation of new services; hiQ 9200 Signaling Gateway, Media Gateway Controller and Call Feature Server; hiQ 20 Registration and Routing Server for carrier-grade IP telephony (H.323/SIP); hiQ 10 Radius Server for authentication, authorization and accounting.

Workers who have the tools, databases, information and news in hand when they are making a sale, identifying the next big idea, collaborating with a client or selecting a value partner will help their companies win in the twenty-first century. Mobile Business, powered by a strong core infrastructure, is all about increasing personal productivity by connecting workers with the resources they need, when they need them.

With Mobile Business technology behind them, backed by an efficient, flexible, reliable converged network, companies can work more efficiently, communicate more effectively, and perhaps even invent the next blockbuster idea that will revolutionize the next century.

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