Telephone networks were used only for the transmission of voice information, and IP-networks for data transmission.

Due to the integration of corporate communications and data networks, and the availability of prepaid VoIP, the efficiency is ensured, which reduces the costs of supporting and maintaining corporate communication systems and increasing their coordination and efficiency. Firstly, it is enough to support only one network, and not two different ones – telephone and data transmission – and, secondly, the merger of the two networks into one eliminates the kind of competition between “telephonists” and “computer workers” that often hinders the business.

The company has a digital telephone network with a single numbering plan, a single management center, with a variety of additional services, starting from the usual for all users of institutional telephone stations to withhold and transfer calls to other numbers and ending with IP telephony-only capabilities.

Why the Internet Telephony costs less?

Ordinary telephone calls require a distributed network of telephone stations connected by fixed telephone lines, the supply of fiber optic cables and communication satellites. The high costs of telephone companies lead us to expensive long-distance calls. The dedicated connection of the telephone exchange also has a lot of excessive performance or idle time during the voice session. Internet Telephony is based in part on the existing network of fixed telephone lines. But most importantly, it uses the most advanced compression technology of our voice signals, and fully uses the capacity of telephone lines. Therefore, data packets from different queries and even different types of them can move along the same line at the same time.

The IP-telephony network (in accordance with ITU-T H.323 recommendations) is a set of the following devices connected to an IP network:

The Gateway – GATEWAY – is a device, for connection of IP-network and PSTN (public telephone network). The gateway can be installed at the user end. Functions:

The Gateway – GATEWAY – is a device, for connection of IP-network and PSTN (public telephone network). The gateway can be installed at the user end. Functions:

  • Answering a PBX / PSTN caller’s call
  • Establishing a connection to a remote gateway
  • Establishing a connection to the called PBX / PSTN
  • Compression, packaging, and restoration of voice (or fax)

Thus, the gateway is the main and integral part of the IP telephony architecture that directly connects the telephone network to the IP network. Gateways of different manufacturers differ in the way they connect to the telephone network, the capacity, the hardware platform, the implemented codecs, the interface and other characteristics. But they all perform the above functions, which are basic for the technology of IP-telephony.

Dispatcher (Gatekeeper)

  • The controller, or GateKeeper, is an additional device connected only to the IP network and carrying all the logic of the IP-telephony network. Its main functions are:
  • Subscriber authentication and authorization
  • Distribution of calls between gateways
  • Billing * As a rule, the dispatcher does not contain a complete billing program, but only a standards-based interface to professional third-party billing systems, as well as an API for developing the operator’s own billing software.

The dispatcher is necessary for any IP-telephony network containing more than two gateways. In the first gateways (in the first host-based versions of VocalTec, Vienna, etc.), the dispatcher functions in their primitive form were performed by the gateway itself. With the development of technology and the growth of IP-telephony networks, the functions of the dispatcher were implemented in a separate module. Although for some manufacturers the dispatcher can physically be on the same system with the gateway, it is logically a stand-alone module.

Monitor (Administration manager)

MONITOR – is an optional module of the IP-telephony network, connected only to the IP-network, used for remote configuration and support of other devices in the gateway network and dispatchers.

Functions: interface for remote configuration via IP-network of parameters of gateways and controllers of IP-telephony network. A monitor is a convenient tool for configuring and administering the network. In the first gateways, standard network applications were simply used for this. Later, in order to optimize the work, the manufacturers of IP-telephony equipment began to produce their own applications for these purposes.

IP Phone

IP-TELEPHONE is a new device that looks like a regular telephone connected to the PBX, but, unlike it, it is connected to the Ethernet port of the switch.

The IP phone provides sound quality comparable to a standard phone and also has programmable speed dialing and other advanced features. The IP phone has a lot in common with the PC. It can work as a normal IP device and have its own IP address. Because the IP phone is fully compatible with the H.323 standard, it can be used to connect to any other H.323-compatible device or software, such as Microsoft NetMeeting.

Being equipped with a graphic display IP-phone, apparently, will soon become the standard, at least in the corporate environment. This display and standard (that is, based on open industry standards Java, XML) tools used to output information to it (of course, along with the ability to work with sound), provide a completely new way to build systems of corporate communications, alerts, and information.