Communication within the Internet is conducted via a system called Internet protocol (abbreviated as IP). In order to uniquely address every device in the network each terminal requires its own individual address, known as the IP address. In addition to individual addresses for devices, there are also addresses for groups of recipients. These addresses are called multicast or broadcast addresses. Devices in the network, such as computers, printers and telephones may also have multiple IP addresses simultaneously. Depending on the version of Internet Protocol being used, IP addresses have a defined notation and are constructed according to a predetermined standard.
The difference between IPv4 and IPv6 addresses
The protocol version most commonly used in the Internet is the IPv4 protocol. Due to the rapid growth of the Internet and the shortage of addresses that has arisen, as well as in order to adapt to new technologies, the IPv4 protocol was revised and the IPv6 version was developed. In the long term the Internet will be converted to operate solely with the more modern IPv6 protocol. IPv4 addresses have four bytes. The address consists of four numbers, with values between 0 and 255 that are separated by a dot. An example of an address is 192.168.1.10. IPv6 addresses consist of 16 bytes and have a different notation, with colons as separators, with an example looking like this: 2001:0bd4:45b2:0000:0000:8e2a:0280:4528.
Both types of IP addresses have a so-called network portion and a host portion. The network mask contains information on which part of the IP address identifies the network and which portion addresses the actual terminal in this network.
The IP address in Voice-over-IP telephony
In order for telephone devices to communicate via the Internet, they have to divide the data to be transmitted into data packets and add the destination and sender addresses to these packages. Unlike traditional, circuit-switched telephony, whereby a kind of fixed connection is created between the caller and recipient and all information is sent along the same route, with VoIP telephony, each data packet finds its own independent way through the Internet, based on the destination address. At the destination, all of the data packets are collected and, where necessary, put back into the correct order. For telephony, IP telephones use both the IP address of called party, as well as that of a SIP server, which controls the connection.