The predictive dialer is a system which would has the ability to dial a large list of phone numbers. It continuously checks which agents are available and are not busy. It then transmits the calls to these available agents. Before the invention of the predictive dialing system, auto dialers were used in a huge number in the field. In the auto dialer process, software is programmed to dial a list of calls automatically. These dialers are responsible for detecting whether a live agent is present for receiving the call. If it finds that port, it delivers the call to that agent. A recorded message can also be played while the prospect waits for the auto dialer to find an available agent. The predictive dialer predicts that when there would be an agent, available for a call and for this purpose, it uses a mathematical algorithm. This is a basic difference between a predictive dialer and an auto dialer. They usually dial a number of calls and based on the number of agents and when the agent is available and then on the basis of its statistics, it switches the potential customer to the available agent, because it has an estimated time interval statistics which an agent spends on a call. Predictive dialers make the life of an online marketer much easier. Some predictive dialer systems have a huge efficiency and productivity level not available in other common dialing systems. The agents have the option during a call to click on the "3rd party message" button or "answering machine message" button . When the "answering machine message" mode is selected, it plays the pre recorded message to the answering machine, allowing the port to be available for the next generated call. If the "3rd party message" button is clicked, it allows for the 3rd party to come on the line to the calling party, and the agent can release the call or release the 3rd party depending on what the call needs. The good news regarding this software is that it is very much cheap and has a flexible architecture that works well in multiple sites and distributed places. Besides its advantages, however it also has a few disadvantages. The old dialers make errors in classifications of calls and some of the older PBXs have difficulty to operate with the configuration of the soft dialer. Other types of dialers include the hard dialers, smart predictive dialers, hosted dialers and hybrid dialers. Each of these types has their own set of characteristics. A company should keep everything in consideration before going for a particular type. A hosted predictive dialer is the type of dialer which is hosted on a web server. One of the outstanding features of this dialer system is that it has the ability to makes the agents virtual. This means that the agents are not required to be physically present at the office and still they can be the part of the call center. This hosted system, just like any other predictive dialing system can detect answering machines, busy tones, fax tones and no answers and deliver only the legitimate calls to the agents. This makes the dialing process more efficient and the agents more fruitful. This dialer has a virtual intelligence system that can distribute calls equally to the available agents. Another important feature of predictive dialer is that it does not dial the National Do Not Call Registry telephone numbers. This can eliminate unnecessary complaints or legal actions against the call center.