VoIP

VoIP is the acronym for Voice over Internet Protocol, and refers to the broadcasting of voice over IP packets over data networks such as the Internet. It can be understood as the technology that makes it possible for the voice signal to travel over the Internet using the IP protocol (Internet Protocol), which means that the voice signal is transmitted in digital form, in data packets, instead of being sent in analog form, through circuits that can only be used by conventional telephony.

A conventional telephone call requires a large network of telephone switches connected to each other by cabling, fiber optics, telecommunication satellites or any other means, which means enormous investment for creating and maintaining these infrastructures.

A phone call over IP, on the other hand, involves compressing the voice and sending it in IP data packets over an Internet connection, over which different calls and even different data can travel, without the need for dedicated links or wasted bandwidth.

The term VoIP actually refers to the protocols that facilitate these calls, although the name is popularly used to refer to the calls themselves, which can be made over any type of connection, from home LANs to mobile data.

One of the major advantages of these calls is that they are not subject to a distance charge, as is the case with conventional calls. On the other hand, VoIP does not depend on the availability of the telephone network (usually fixed), but on Internet coverage to be able to transmit calls; the downside is that if Internet coverage is not good, the call will also lose quality.

It should be noted that VoIP technology, in addition to being very common, especially in mobile applications, can also be used in conventional fixed telephones, with various equipment and configuration options, to digitize the voice from the telephone and send it over the Internet.

Basic VoIP Infrastructure

The basic VoIP infrastructure has the client-server model:

• The Client is the one at both ends of the communication channel, who establishes the calls. Information that is received through the user's microphone (input) is encoded, packaged, and sent; likewise, when received, it is decoded and reproduced through the headphones (output).
• The Server is responsible for handling the real-time operations of the communication, which include: call time counting, routing, service administration and control, and user registration, among others.

The endpoints (clients) of a VoIP infrastructure are the devices used by users to communicate. Implemented in both hardware and software, they perform the functions of traditional telephones.

In general, there are 3 main types of VoIP endpoints:

• Software-based: understood as a system (program or application) that is installed on a computing device (computer, tablet, smartphone), and uses its resources (usually microphone, speakers, screen, among others) to make or receive calls. They are known as softphones.
• Hardware-based: these devices look and function like a normal telephone, but are connected directly to the data network instead of to the conventional telephone line. They are called hardphones.
• Use of an ATA: An Analog Telephone Adapter (ATA) allows a standard conventional telephone to be connected to a network connection (Internet) for use with VoIP. ATA is a converter that takes the analog signal from the traditional telephone and converts it into digital data for transmission over the Internet.

In the Server part of the VoIP infrastructure, equipment called IP-PBX (IP switches) is usually installed, which in practice functions as an IP telephone switch, to provide communication services over data networks.

An IP telephone switch or IP-PBX (IP Private Branch Exchange) is a device designed to provide communication services over data networks. An IP-PBX is in fact a telephone switch directly connected to the public telephone network through trunk lines, to manage not only internal calls, but also incoming and outgoing calls with autonomy over any other switch.

An IP-PBX consists of:

• Gateways: They transparently connect VoIP networks to traditional telephony networks.
• Gatekeepers: They are at the heart of VoIP networks. They are responsible for user authentication, bandwidth control, routing, billing and timing services, among others. They can be considered as an equivalent of traditional telephone switches.

VoIP Protocols

VoIP technology requires a number of protocols to facilitate delivery of voice communications over the Internet. Some of the most well-known are:

• H.323 protocol: a standard created by the International Telecommunication Union (ITU) that defines the way to provide communication sessions over network packets, providing various bandwidth management and call control functions. It includes a set of standards for multimedia information, referring to endpoints, equipment and services, and establishing signaling in IP networks. It is independent of the network topology and allows more than one channel of each type (voice, video, data) to be used at the same time.
• SIP Protocol: The Session Initiation Protocol (SIP) was developed by the Internet Engineering Task Force (IETF) as the standard for the initiation, modification and termination of interactive user sessions involving multimedia elements such as video, voice, instant messaging, online games and virtual reality. Its syntax is similar to the HTTP and SMTP protocols, used for web page services and mail distribution, respectively. This similarity is natural, since it was designed so that telephony could become just another service on the Internet.
• IAX Protocol: The Asterisk Inter-Asterisk eXchange Protocol (IAX) is used by Asterisk (an open source IP-PBX server) to handle VoIP connections. It was developed for VoIP signaling in Asterisk, allowing it to prioritize voice packets in an IP network (QoS: Quality of Service). It uses a single UDP port, typically 4569, for communications between VoIP endpoints. It is considered a robust and simple protocol compared to other protocols, and can be used to transport virtually any type of data. Today the term IAX generally refers to the IAX2 protocol, its second version, as the original has been discontinued.

Other proprietary protocols of VoIP service providers are:

• UNIStim: proprietary protocol of Nortel (Avaya).
• MiNet: proprietary protocol of Mitel.
• CorNet-IP: proprietary protocol of Siemens.
• Skype: proprietary peer-to-peer protocol used in the Skype app.
• SCCP: proprietary protocol of Cisco.

One of the challenges VoIP is facing is that the protocols currently in use are not always compatible. VoIP calls between different networks may not be successful if they use different protocols that are not compatible. This problem will be solved when a standard appears, either if it is created or if any of the above mentioned standards is massively used.

Benefits

The first and most important is the cost: a VoIP call is in most cases much cheaper than its equivalent in conventional telephony, which is basically due to the fact that the same network is used for data and voice transmission.

Conventional telephony has fixed costs that IP telephony does not have, hence the latter is cheaper.

With VoIP it is also possible to make calls from any location where there is Internet connectivity, since IP endpoints can be used from any location where a connection is available.

Most VoIP providers deliver features for which conventional telephone operators charge separate fees. A VoIP service includes, at no additional cost: caller identification, call waiting, transfer, voicemail etc. It is als opossible to integrate other communication products, such as instant messaging, e-mail and video conferencing.

On the other hand, organizations using VoIP services require less maintenance costs, since it will not be necessary to maintain two different networks (data and telephone): VoIP allows routing telephone calls through the same data network that is used.

Similarly, VoIP improves productivity and response time, as communication is not restricted by location, device or access, so local phone calls can be automatically routed to a VoIP phone, no matter where it is connected to the network.

Drawbacks

Currently, most of the problems in the use of VoIP are the result of technological limitations, which must be solved as a result of the constant innovative evolution of the technology; some of them are:

VoIP requires a reliable Internet connection and is sensitive to bandwidth constraints: when insufficient, phone calls can experience latency, which can cause delays and dropped calls.

VoIP requires an electrical connection, and in case of a power outage, users cannot make calls from their VoIP phones, as VoIP endpoints require power to operate, while conventional telephones only need the telephone cable.

Emergency calls with VoIP phones can be difficult because IP addresses do not provide the exact location of callers.

From a security standpoint, VoIP calls are transmitted over the Internet or potentially insecure networks, which poses privacy and security risks that do not arise with a traditional telephone service. In this sense, the VoIP infrastructure can also be damaged by the effect of a virus, worm or denial of service attack, both from the devices involved, as well as in the vulnerabilities of the network through which the data is transmitted. In this sense, protecting the data network and end-to-end encryption of the call can minimize the adverse effects.

In a general sense, it is expected that the technological evolution of VoIP will overcome these drawbacks and eventually completely replace conventional telephony.

For the protection of voice calls, messages, and files, Protelion offers Protelion Messenger, a product that uses the point-to-point encryption of Protelion technology for security. In this application, the contacts in the Address Book are only the users of the protected Protelion network, who have symmetric keys for encrypting the information between them, which guarantees that no one else can pick up and listen to the conversation or read messages sent through the application, in addition to the user having the certainty that these keys are generated by their corporate network and are not located “somewhere” in the cloud.