Many innovations within the telecommunications industry, one can hardly overlook the significance of the development of Softswitch technology. To gain a proper appreciation of the benefits of Softswitch, let's get down to basics of what this technology is all about.
What is a softswitch? A softswitch is a centrally located device within a telephone network that is used to link calls from one telephone line to the other, through the use of specialized software. The functions of the softswitch were earlier undertaken by hardware, with physical switches being used for the routing of calls.
The softswitch is generally housed in a building belonging to the telephone company. This is called the central office and is linked to other properties owned by the particular telephone company and to other telephone companies.
Softswitch literally implies the operation of switches made from electronic textiles a trend that combines the efficiency of electronics with the visual appeal of textiles. In layman's terms, the basic function of the softswitch is to separate the hardware and software of a circuit switched network.
How does it work? There are different components in the system that manages the different functions. The Softswitch is controlled by the Call Agent. This is a sort of administrator that regulates applications such as services, billing, signaling and routing of calls. The Call Agent has the capacity to monitor a number of Media Gateways over areas that are separated by considerable distance. This has become possible through the use of a Transmission Control Protocol/Internet Protocol or TCP/IP connection.
The Media Gateway functions by linking different kinds of media streams to set up an end-to-end pathway for the voice and data transmission in the call. It may be equipped with a number of interfaces of different kinds, allowing for connection to different kinds of networks conventional Public Switched Telephone Network or PSTN systems involving DS1 or DS3 (Digital Signal) ports.
On the other hand, it may be equipped to accommodate interfaces linking up to ATM (Asynchronous Transfer Mode) or IP systems. Modern systems will also accommodate Ethernet interfaces for VoIP applications. The Call Agent directs the media gateway to link media streams between the interfaces, making it possible to connect the call.
The Media Gateway may also be linked to any number of accessing gadgets. These could be analog telephone adaptors or ATAs (Analog Telephone Adaptor) with a single RJ (Registered Jack)11 socket for the telephone jack; the Media Gateway could also be connected to a PBX (Private Branch Exchange)or an Integrated Access Device (IAD), which has the capacity to accommodate hundreds of telephone connections.
Normally the larger access devices are housed in buildings in close proximity to the clients for whom they are intended. All it takes is a pair of copper wires to link the end user to the IAD.
PBXs and devices of medium size would be suitable for use on commercial properties. Single line devices would be more suitable for residential premises.
Recent developments. The International Softswitch Consortium or ISC is attempting to upgrade conventional networks to enhance their efficiency and accommodate more softswitch features. So far there has been a limited degree of success in that the principal elements of conventional networks have been delinked. The transmission function of telecommunications networks is expanding to make better use of Internet Protocol or IP.
One aspect of the drive towards delinking is demonstrated by the use of specialized mediation and gateway equipment to link circuit based networks to IP based networks to facilitate the use of VoIP. Even so, there is much more involved in this process than simply delinking the components of the system.
The delinking of Intelligent Networks or IN has only been partially successful. This has fallen short of the expectations of those who support softswitch technology. They claimed that the separation of the components of intelligent networks would provide better scope for the inclusion of more services.
The general feeling is that Intelligent Networks would not harmonize with call controls that are dependent on activation by voice. It was felt that new controls would be required which could be based on sessions and be receptive to multimedia services as well as voice and data applications.
Another initiative with a similar objective has been undertaken by the Internet Engineering Task Force or IETF to stipulate the potential for networks that combine features of Internet Protocol and Intelligent Networks. The goal of such endeavors is to create a softswitch that does not operate on circuit-based switches and that makes use of intelligence and logic-based features.
The dispersal of functional tasks will result in improved efficiency and cost effective operation. The function of switches will then be restricted to switching alone, while other components will be geared to furnish service logic and network monitoring. The dispersal of service logic implies that there will be greater flexibility in the development and deployment of applications and services at different locations within a network.
Rocky road ahead? Nevertheless, it is expected that there may be some problems along the way. For one thing, more conventional service providers have their reservations about going along with the initiative to advance Softswitch technology. Apart from that, Softswitch will have to be integrated with conventional networks since Softswitch will not become functional everywhere at the same time.
Another factor that is causing concern is that there may be special requirements to enable dissimilar networks to function together. Such requirements will involve issues such as verification and endorsement of network components and applications. Conventional networks utilize protocols such as SS7 to manage these functions. However, as networks become more and more sophisticated, these issues will also become far more complex.
Companies investing in Softswitch can avail of various advantages offered by this technology. One of the most important of these is the de-linking of call processing functions from the process of physical switching monitored by the Media Gateway. This kind of separation of functions allows a single software platform to be utilized for different kinds of media.
Apart from the fact that Softswitch offers scope for greater adaptability, it also enables less prominent vendors with greater potential to concentrate on the application of their choice. However, as a result of reservations about the reliability and financial implications of deploying this technology, migration has taken place in stages. Since the majority of recognized carriers have made a substantial investment in TDM or time division multiplexing technology, they are hesitant about replacing it with Softswitch unless it proves to be more economical.
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