Voice over IP (VoIP), also known as IP telephony, describes a technology that enables telephone calls to be made over a data network. This allows the same network to be used for data transmission and telephony. As this means that the provider only needs to operate one kind of infrastructure, it results in considerable savings, resulting in conventional analogue and ISDN telephony gradually losing its importance, to the extent that they will be replaced entirely by Voice over IP in the long term.
The technology of Voice over IP
In Voice over IP telephony, the voice data is digitised and put into single IP (Internet Protocol) packets. These packages are provided with destination and sender addresses, allowing them to travel through the network nodes, hop-by-hop, to their destination. Unlike with conventional telephony, no fixed connection is created between the subscribers, so the individual packets can take different paths or even overtake each other during transit. At the destination the end node sorts the packets back into the correct order and the terminal converts the data for playback as analogue signals.
To establish the connection, most VoIP systems use the so-called SIP (Session Initiation Protocol) standard. Each participant has a unique SIP address and registers themselves with a SIP server. To establish the connection the device initiating the call will contact the SIP server and then receive the IP address of the desired subscriber.
PCs with an Internet connection and headset or speakers and microphone or Voice over IP enabled phones can be used as Voice over IP phones. In order to use conventional analogue or ISDN telephones for a VoIP connection, the subscriber needs an adapter or a VoIP telephone system.
The advantages of this technology
In addition to savings for providers and end users through the exclusive use of a single infrastructure, Voice over IP provides a number of other advantages. Because the terminals are directly connected to the data network, completely new functions can be created. For example, a telephone can display additional information about the caller or automatically initiate a call by clicking on an address on the PC. Software can be used to merge data and voice services into powerful solutions. In addition, the telephone system can be completely relocated as a cloud service in the network, which makes for greater flexibility, because there is no need to install and operate hardware.