2. “IP-telephony”, “VoIP”, “Unified Communications”:
Sorting out the Definitions

Everyone has probably heard about things like «IP-Telephony», «VoIP» and «Unified Communications». However, not everyone has a clear picture what all these terms mean, since there are numerous discussions, articles and opinions going on around.

So before proceeding with details, let’s start with the definitions of several technologies that change the way we communicate.

The «IP-Telephony» and «VoIP» terms are often used interchangeably. Nevertheless, there is a difference.

VoIP

VoIP (Voice over Internet Protocol) is a general term for several technologies used for transmitting voice over an IP network.

VoIP — is not exactly the «IP-Telephony» thing in the sense that will be defined later. VoIP can use public Internet to carry the voice traffic, for instance, Internet-radio.

Another way to use VoIP is to use IP-network to connect traditional phone systems. When doing so, the connection with an IP-network is administered by special gateways that can be either PBX modules or standalone devices. In this case, IP-network is a transit agent, so PBX users may not even know it exists. 

Connecting analogue PBX

Not every IP-network is suitable for VoIP to function. Packets with digital audio should be delivered without a loss and with minimum latency, otherwise there is a risk that restored voice will not be smooth anymore. To ensure the highest transmission priority of digital audio over other IP packets, there should be mechanisms that guarantee the quality of the transmission. In general, such mechanisms are known as QoS (quality of service). An IP-network with necessary QoS mechanisms for VoIP is referred to as a multiservice network.

IP-telephony

IP-telephony is a set of hardware and software that, together with VoIP technologies, enable voice communication over an enterprise using IP as a native transport for voice and call signaling.

The main components of an enterprise IP-telephony network are:

• IP-PBX – software that has functions of a traditional phone system and is installed on one or several enterprise servers.
• IP-phones – the phones that get connected directly to LAN.
• Gateways – the devices that join an IP-network with traditional phone systems (PSTN and analogue PBX) or connect analog phones, faxes and modems to an existing IP-network.

Enterprise VoIP network topology

Compared to a traditional phone, an IP-phone has many more functions and, in some cases, it can even be used to replace a computer to organize a workplace.

IP-telephony forms a unified communication network, manages a set of available phone numbers, a set of specific services and availability of IP-telephony service for users regardless of their current location (that goes beyond just a main office and may be at a corporate branch, at someone’s home or even when someone is on a trip).

Corporate or regional branches are naturally integrated into an IP telephony network as soon as such a branch gets connected to a corporate IP-network. There is no need to setup a stand-alone PBX in a branch. Connecting IP-phones to a LAN, in this case, is enough.

Unified Communications

Unified Communications is a set of applications at the junction between “the world of computers” and “the world of phones”. The main purpose of Unified Communications is to speed up and functionally enrich interaction between company employees and the company and its clients.

The technological backbone of Unified Communications is IP-Telephony. But while IP-telephony solves the same tasks as traditional phone systems (though in a much more effective way), Unified Communications is the way to optimize business process.

Enterprise VoIP network organization

Unified Communications software solutions optimize the enterprise business processes by integrating all the forms of communications (e-mail, IM, phone, video, mobile) and enterprise data.

So, let’s summarize: 

• VoIP is a technology used to transmit the data over IP network.
• IP-telephony is a set of software, hardware and technologies that use VoIP to organize a telephony communications over the enterprise.
• Unified Communications is a set of applications to integrate all forms of enterprise communications with business data.

Unified Communications solutions utilize the IP telephony system, which, in turn, is based on VoIP technologies. IP-telephony requires VoIP to send calls over the network, but VoIP does not need IP-telephony. Unified Communications require IP-telephony, but IP-telephony can exist without Unified Communications.

Read the next chapter: 3. The Classification of Unified Communications Solutions

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