VoIP
.... One source stated, “…these IP phones or VoIP gateways allow you to make and receive phone calls exactly the same way that you currently do, except, you can save money on phone service, long distance, and gain an abundance of features that are not really offered by the phone companies today.”(Neuworld, 2004) Rather then using the old circuit switching concept or making telephone calls, VoIP uses packet switching. Packet switching is the method of sending small parts of data with an address included to let the network know where to send it. When the packets arrive at their final destination, it is then pieced back together into its original form. With VoIP, the three different ways to make telephone calls are computer to computer, computer to telephone, and the last being telephone to telephone. The simplest way to make calls with VoIP is with the computer to computer method. To use this method, the user must have special software, a microphone, speakers, a sound card and obviously, an internet connection. The only incurring charges for this method should be by the users’ internet service provider. The next method, computer to telephone, is similar to the previous because of the need for software, but may charge a fee for usage. Then you have the telephone to telephone method of connecting. Users are able to connect directly to any standard telephone through special gateways on the globe. Customers must call one of several companies’ gateways then enter the desired phone number. One of the most convenient aspects about Voice over IP telephone is that it is portable. The TA, or telephone adapter that is provided by the telephone company, can be utilized anywhere with a high speed internet connection. For example, if a subscriber is taking an out of town trip and stay in a hotel with broadband connections, they can hook the telephone adapter up to the internet then connect any phone and make calls just as if they are home. A very neat feature that isn’t available with normal telephone service is a “locate me” feature. This feature allows for the consumer to have telephone calls rerouted to up to ten different phones in case he/she isn’t at home to take the call. Along with the unique online voicemail management feature, most VoIP services also include 3-way calling, personal conferencing, call waiting, call forwarding, and many others. As with most things in the world, Voice over IP have rules, lots of rules, called protocols. Session Initiation Protocol or SIP for short is a standard for establishing Voice over IP connections. It is an application layer control protocol for creating, modifying, and terminating sessions with one or more participants. This protocol is similar to the hyper text transfer protocol; otherwise know as “http”, because it deals with a client/server relationship. Media Gateway Control Protocol defines communication between call agents and telephony gateways. MGCP relies on simplicity and reliability so that workers are able to focus on local systems. This protocol allows a central coordinator to monitor events in the phones and instructs them to send media to any given address. RTTP or Real Time Transfer Protocol is an end-to-end protocol utilizing transport layers for data that has real time properties. RTP supports the transfer of audio and video data over packet switched networks and allows the receiver to detect any losses and provide timing information so that the information can be corrected and compensate any delays. Real Time Streaming Protocol is another client server protocol that provides control over the delivery of real time media streams. With this protocol channel choices can be made like UDP multicast and TCP. One of the most important protocols is the H.323 protocol. The H.323 protocol defines ...