Understanding Softswitch
Think you are taking to your friend by stretching a telephone line to his home from your home. You only talk with your friend. Soon, you want to talk with many other friends. So, it is not possible to stretch separate line from your home to many other friends home. What happens then, there established a Service Station called “Local Exchange”.
Each person is connected to local exchange office. So, when they call to local exchange, exchange transfers the call to called person’s line from a switchboard that is liked with all local telephone lines. This transfer of telephone call had done by manual operators (A person called Telephone Operator) serviced in the exchange station.
So Telecommunication is a network of basically 4 entities:
- Subscriber (You, who make the call)
- Telephone Operator (A person who connect the call)
- Telephone Line (Copper or Fiber Optics)
- Your Friend (Who receive the call)
If you want to make this network stronger, you can’t strengthen the entities in two ends (You & Your Friend), you need to improve the middle two entities (Operator & telephone line). And exactly, that’s what is going on in telecommunication till its invention a century before.
Soon after, people wanted to talk beyond their local areas. So, nearby Local exchanges connect together by ‘Trunk lines’. Equipment at the exchange examines the dialed telephone number and connects that telephone line to another phone line, or to a trunk to a distant exchange. Most of the local exchanges in the world are connected like this to each other, forming the public switched telephone network (PSTN).
At the beginning of 1900, Telephone Operators were in a position to listen to private conversations as being in complete control of the call. So, to reduce labor costs and to ensure privacy to the customer, telephone companies have motivates to use an automatic telephone exchanger that does not require any human intervention.
That’s leads to the invention of Electromechanical Switch that can handle phone calls instead of manual man hauled switching. This electromechanical switchboard itself could translate the call into the needed routing information. In this system when a customer-dialed long distance calls; he/she needs to wait 10-20 seconds to get call connected.
Switching technology leapt forward after `70s while digital electronic switch replaces electromechanical switches. This switch could handle a much higher calls; initially 350,000 calls per hour.
Now, a long distance call can be connected within 1-2 seconds.The increasing demand for Telephone conversation also goes beyond national boundaries, people needed to call internationally. First, there was copper wire stretches under major seas of the world to get Continents connected. During `90s those submarine telephone cables were replaced by fiber-optic cables, enabled to transmit more calls at one time. Over 1 million calls can be placed in this fiber-optic cable at a time that is 25 times higher than that of the last copper cable.
With the invention of “Word Wide Web” , data traffic on global telecommunication cable has increased dramatically. In 2000, the volume of data traffic exceeded the volume of voice traffic for the first time in human history. This data travels over the world-wide telecommunication networks in packets, rather than over the dedicated circuits that have carried voices since the 19th century.
Now, the era of computer and internet begins that demands all telephone companies of the world evolve from historic circuit switching to packet switching. This means future customers will be billed for their total data usage (like for example 30 megabyte of usage); not for their total call-time. But there stills remains decades for all telephone companies of the world to transfer from this long established circuit-switch system to packet-switch technology.
But things do not stop and wait for replacing the whole PSTN to packet switching network. Many big bodies like Skype, Vorizon, and Vonage come across the global telecommunication network and they are called VOIP providers.
VOIP technology converted a Voice call to Data (Data Packet) and sends it over internet to reduce the call price. You can now call from your PC to any land phone or cell around the world. When you make call from Skype on your PC, your packet switched (give hyperlink) voice travels over the internet.
But your friend’s land phone or cell is on PSTN network. So, it needs some mediatory to translate your packet switched voice to circuit switched voice. This mediatory is called “Gateway”. Gateway connects two incompatible types of telephone network system. These gateways are simply routerswith built in operating systems that enable the recognition and routing of voice traffic from IP to PSTN network through the use of stationary dial peers.
All the mobile operators and land phone operators in a country are connected with some Gateways. A Gateway allows IP-originated calls to terminate to the PSTN and vice-versa or may simply provide a means for a person to connect a telephone to the Internet.
Now, let’s get back to early telecommunication system. You call the operator, he listens what number you want to call and connect the call to specific line. So, Connection of call from its source to destination involves: A logic & a physical connection
- A logic: You call the operator, his brain (logic) listen and
- Physical connection: The operator place your call using switchboard.
In VOIP, this operator is substituted by Media Gateway Controller (MGC) which is a server run by software called Softswitch. Our company provides such a softswitch which is branded as “SyncSwitch”.
The softswitch works as a human brain (operator) in a MGC. Softswitch has the robotic intelligence to understand what number a caller is dialing and what path the call should follow to reach the called person’s phone.
The Physical Connection part of a call is performed by different entities called Media Gateway. The MGC aka soft switch gets connected with different Media Gateway by internet. Typically the larger Media Gateway will be located in a building owned by the telecommunication company in different countries.
So, an MGC can control several Media Gateway located in diverse geographical location; internet helps them to get closer and connect with each other. The connection between a softswitch and a Media Gateway is established by reciprocal deal between Media Gateway Controller Company and Media Gateway Company. The software architecture of a soft switch has the technology to handle such deals.
Let’s take an example how a Softswitch and A Media Gateway works together. Suppose you make a call through SyncSwitch software (Client Software) from your PC to friend’s mobile who resides in the UK and using Vodafone mobile. Your call will first reach the SyncSwitch central MGC server located in USA, in there the SyncSwitch software will identify which country you are calling .Then it will route the call to a gateway located in UK; where the Gateway will translate (from IP packet to PSTN) and route the call to Vodafone network.
You Call >> SyncSwitch >> Protocol Conversion & Route to Local Gateway >> Your Firend`s Phone
Now, if we don’t talk about how this software intelligence in a softswitch works; the total scenario will be unclear. So, let’s talk about technical tasks performed by a softswitch. Softswitch mainly handles three tasks:
- CODEC Processing
- Call Routing to Media Gateway
- Billing