ZTE’s Softswitch System Builds Mature NGN

China Telecom started a large-scale Softswitch equipment test in 2002, and launched a lot of NGN commercial trials in different cities. Besides, the Softswitch network of China Netcom has covered a large number of areas in China, while China Mobile is using the Softswitch technology to offer new services as a supplement to those in its backbone network. Moreover, Carriers such as China Unicom and China Tietong have put their Softswitch systems into commercial use after relevant tests. All the facts indicate that the Softswitch application is growing rapidly.

    ZTE Corporation has been following up and studying the Softswitch technology since 1998. It joined the International Softswitch Forum (ISC) in May 2000. ZTE’s Softswitch products have been found in the business territories of all Chinese telecom carriers and in the telecom markets of Hong Kong, Romania and Philippine since August 2001 when China Netcom chose ZTE’s Softswitch products for its trial commercial Softswitch office in Ningbo, a southeastern city of China. The reason for ZTE’s success is its powerful NGN research and development capabilities and the proper positioning of its products in the market.

1 Standardization of Softswitch-Based Protocols
The Softswitch architecture includes many protocols, like medium gateway control protocols such as MGCP and H.248, the intelligent terminal protocol, Session Initiation Protocol (SIP) and signaling protocol. ZTE plays an active and important role in making international and domestic multiple standards for Softswitch-based protocols. ZTE’s Softswitch system available strictly follows the standardized protocols. It has passed the interworking test held by China Unicom and China Telecom with wide recognition.

    Since 2000, ZTE has been actively taking part in making the Softswitch industry standards authorized by the Ministry of Information Industry (MII) of China and playing an important role.

    In 2001, ZTE started participating in drafting carrier’s enterprise standards and since then ZTE has greatly promoted the Softswitch market and product trials.Since 2002, ZTE has been cooperatively working with carriers to setup good NGN business models during the construction of carriers’ NGN networks. At the same time, ZTE kept a good cooperative relationship with domestic research institutes and carriers in all respects of the protocol standardization.

    ZTE became one of the major members of the NGN technology research project of the National "863" High Technology Plan of China in 2002. It also participated in the study of "An Overall Technological Scheme for Softswitch to Support Multimedia and Mobile Services", a project of the "863" Plan, which was checked and accepted in January 2003.

    In 2003, ZTE not only led the establishment of 42 domestic Softswitch standards, but also submitted international standard proposals of Address Resolution Principles of NGN and Service Architectures of NGN to ITU-T. And ITU-T SG13 admitted all the proposals. The former has been written into Y.NGN-SRQ (draft) of Q11 and NGN 2004 Project of Q12, and the latter written into Y.NGN.FRA of Q1.

    Besides, In July 2004, ZTE obtained two editor seats to respectively draft Y.e2eqos.1 and Y.ipaqos, two standards for NGN QoS at a meeting of the NGN Joint Rapporteur Group of the International Telecommunication Union (ITU) in Geneva.

2 Quality of Service (QoS)
QoS is an important factor for the development of Softswitch technology. ZTE thinks that QoS should be guaranteed at all levels. All parts, such as the bearer network, network planning and system equipment, contribute to the whole QoS. A single part may do harm to the QoS of a whole system.

    For the planning of a bearer network with end-to-end QoS guarantee, various factors should be taken into consideration: proper bandwidth design and network planning are first required, Since proper bandwidth is the most important condition to guarantee QoS; the core layer of a bearer network needs adequate capacity and efficient and quick forwarding capability to assure quick forwarding of services; and technologies such as Differentiated Service (DiffServ), Committed Access Rate (CAR), congestion control and Visual Local Area Network (VLAN) division should be applied at the edge layer to assure service access and service classification.

    ZTE uses the jitter buffer and traffic control technologies in its Softswitch equipment to guarantee QoS. The voice QoS is assured by multiple means such as by technologies supporting echo cancellation and delay jitter, mute detection, Comfort Noise Generation (CNG) and dynamic buffer adjustment. ZTE’s Integrated Access Devices (IAD) also supports both 802.1Q VLAN and VLAN TAGG to separate data from voice at the access layer and two priority queues in accordance with the 802.1p recommendations to deploy different service priorities and to further implement DiffServ-based QoS.

    The fact that ZTE was chosen by ITU to draft two important international standards, that will help to shape the future of the NGN world, fully demonstrates that Chinese enterprises have become a globally recognized leader in the NGN QoS research.

3 Equipment and Service Security
As all equipment is connected with the Internet, it is necessary to take corresponding measures to assure the security of equipment and services. All core network elements and Web servers need the protection of firewall to guard against attacks of illegal users. As the scale of Softswitch application is enlarging and more and more network element equipment is being put into use, equipment authentication has become a necessary and important issue to prevent illegal users.

    ZTE provides a reliably encrypted authentication mechanism for all Softswitch network element equipment authentication especially for terminal access authentication. Only the equipment that has passed authentication is allowed to access to the network. Furthermore, in order to reduce the security risk of terminal access as far as possible, the security authentication mechanism is defined by protocols such as SIP and H.248, and algorithms such as MD5 are used to encrypt and send key parameters.

    In addition, H.248 and Media Gateway Control Protocol (MGCP) also define the transfer by the IPSec protocol, which assures security of signaling transfer besides terminal access security. Related network element equipment of ZTE’s Softswitch system has a built-in security self-check tool. Therefore, it can spontaneously reject any suspect intrusion and report to the network management system. It also can refuse irrelevant network requests from the outside in a real time way.

    In March 2004, ZTE was granted the right to draft a new ITU-T standard, X.msec-3 as an editor at the fifth ITU-T SG17 (data network and telecommunication application software workgroup) plenary meeting in Geneva. It is the first time for a Chinese enterprise to draft international standards in information security. ZTE’s leading position in information security research provides a full security assurance for its products.

4 Terminal Management and Power Supply
As the capacity of the Softswitch network keeps growing, more and more terminals are accessing to the network. Therefore, it is greatly necessary for terminal management. ZTE’s Softswitch management system can manage
multi-protocol based terminals and multi-manufacturer based terminals, implementing the real openness of terminal management.

    In the existing Public Switched Telephone Network (PSTN), the power for voice terminals is supplied at the office end. The telephone can still be used even if the power at a user’s home is cut. But the electrical power for some intelligent terminals and IAD is locally supplied, and this kind of terminals cannot be used when there is a power failure. The problem is related to many factors, including the power supply for the data network. Fortunately, ZTE’s Softswitch system can provide multiple solutions. For example, one solution is the Local Area Network (LAN) based terminal power supply. Pairs 4/5 and 7/8 of Category 5 cable are used to supply electricity for user terminals, and other pairs for data transfer.

5 Openness of Service Platform
The highlight of the Softswitch system is its capability of service provision. How to make the future service provision quicker and more convenient? The answer is that equipment vendors should provide fully standardized service interfaces to allow service providers to just focus on service development regardless of its implementation at the bottom layer.

    ZTE’s Softswitch system provides standard Parlary API interfaces in line with Parlary API specifications and allows service providers to develop services independently.

    Currently ZTE’s Softswitch system can provide the following services:

• PSTN services.
• Public IP-phone Bar.
• IP Centrex for group users.
• Intelligent services supported by broadband-based IP Service Content Providers (SCP).
• IP value-added services, such as the Web 800 service, Voice Mailbox Service (VMS), Web Conference, Voicemail, Phone Conference, Prepaid call, ONLY service and some Unified Messaging Services (UMS).
• Soft Digital Assistant (SoftDA) services.
  

    For example, the Romanian nationwide Softswitch network constructed by ZTE is able to cover 13 major cities all over Romania and provide multiple services including data, voice and video services.

6 Business Models
The Softswitch technology has been successfully put into commercial use by some operators. However, as an emerging technology, Softswitch still has some problems in both technology maturity and market promotion, which requires all related parties to closely cooperate and solve them.

    First, it is necessary to provide Softswitch with a reliable external data network with guaranteed QoS. Softswitch technology is closely combined with the data network. All Softswitch equipment, as a plane structure, is connected to the data network. All signaling and media bearing are completed through the data network. Therefore, the quality of the data network decides, to a great extent, the QoS of the Softswitch system. To ensure the quality of data network, more advanced technologies is required. With the application of Multiple Protocol Label Switching (MPLS), DifferServ and Reservation Setup Protocol (RSVP), and the development of IPv6 and other advanced technologies, the IP network will really become an operational and manageable data network, no longer to be the existing "Best Effort" network.

    Moreover, Softswitch development also relies on people’s understanding of new services and carriers’ right business model aiming at Softswitch. Free-of-charge effect brought by the Internet development has affected the consumption pattern of many users. They think that all Internet-based services should be free of charge. However, this will prevent carriers from making profits, bring users services without QoS, slow technology development, and finally worsen the Softswitch market environment. Therefore, carriers should first get rid of traditional business concepts and models, and use the flexibility of technologies to gradually foster the Softswitch market and build up consumers’ new consumption habit. Only in this way can the Softswitch market grow well. Moreover, the development of Softswitch also brings a revolution in the communication industry, which is a thorough change from the existing technologies. So carriers have to give up following the traditional business model for PSTN networks, and think about how to operate the Softswitch system to assure continuous development of the market.

    During the quick development of Softswitch market, equipment manufacturers and carriers need adhere to market-orientation, guide technology development and cultivate the market in the construction of Softswitch networks. In today’s NGN field, new technical standards and protocols keep emerging and growing, so carriers should, guided by market- and user-orientated business strategies, continuously expand the market and develop new operation and maintenance ideas to prepare well for the large-scale commercial use of Softswitch.

    The successful commercial use of ZTE’s Softswitch system is also ascribable to the market environment. Since new carries want to quickly develop business in competitors’ preponderant territories, Softswitch technology is indeed the best choice for these carriers lacking brand advantages, client resources and access resources. Based on the existing data network or sharing one data line with traditional services, the Softswitch technology can provide multiple new services to alleviate the investment pressure of the emerging carriers and attract more subscriber.

    Softswitch can be used to replace the tandem office and end office. In addition, it can distribute services on the existing toll backbone network to the data network as well as provide new services, which gives veteran carriers a good means to stabilize preponderant client resources. Therefore, it is the market that creates opportunities for ZTE’s Softswitch system and makes its successful commercial use inevitable.

References
[1] RFC3435, Media Gateway Control Protocol (MGCP)[S].
[2] Gong Shuangjin, Liu Duo. Key NGN Technologies[M]. First Edition. Beijing: National Defense Industry Press, 2003.

Manuscript received:2004-08-26