IP and IT telephony are essentially the same thing. This type of telephony is becoming more popular every day. Until recently, the Internet and telephone were completely different things, which could not unite in any way. Now, IP (IT) telephony has appeared. This is a type of communication thanks to which a user of a personal computer can easily call relatives, friends or colleagues without leaving his workplace. In this case, communication with another user will be carried out using the Internet itself or some other IP network.

History of appearance and use

The communication technology itself appeared a long time ago, back in the 80s. IP telephony technology began to be actively distributed and used already in 1995. The technologies that were used before are no match for what is used today. For example, sound compression was previously carried out using GSM technologies. Until recently, this technology was not used in any way in Russia, and in the United States of America it began to be used only about 7 years ago. Today, completely different technologies are used to transmit information (including audio compression and decompression), which take IP telephony to a completely different level.

Advantages of IP telephony

This type of connection has big amount advantages. For example, from an economic point of view, a person will spend much less money on making such calls using IP telephony. This will be even more relevant if a person often makes long-distance or international calls. The next advantage is that a person can easily make a call either to the interlocutor’s computer or to a telephone. In order to use IP telephony, you need to connect special gateways for IP telephony. With the help of these gateways, the user gets the opportunity to make a call to both the phone and the computer. The principle of operation of such telephony is that this gateway, which on the one hand must be connected to the telephone, and on the other to the IP network, receives a special signal and digitizes it. Then, after this process is completed, the incoming signal is divided into special data packets and compressed to the optimal size. This data is then sent to a special address.

A modern communication standard that involves transmitting voice and messages via the Internet. It is independent of analogue lines and mobile channels. To organize corporate communications, you only need an Internet connection and IP telephony from UIS.

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Advantages of IP telephony

1. Minimum expenses:

can be connected additional numbers without laying a cable;

no need to buy PBX and other expensive equipment;

SIP telephony support is handled by the provider, which reduces the load on the client’s IT service.

2. IP telephony scalability:

when opening new divisions, the same company contacts are maintained;

to expand the call center you do not need to buy additional equipment;

When carrying out promotions and other events, special telephone numbers are connected within 10–15 minutes.

3. Efficiency:

You can organize communication in the office in one day. Setting up external communications takes a little more time;

when a company moves, SIP lines continue to function, so business processes are not interrupted for a minute;

automatic forwarding of calls from the company's single numbers directly to the necessary departments and employees saves a lot of time, which improves customer attitudes towards the company.

4. Expanded functionality of the Virtual PBX for processing customer calls:

optimization of call distribution and communication quality control tools allow you to increase the conversion of calls into sales;

dynamic call tracking, event notifications and auto-calls based on passes ensure lower cost of leads;

Bringing call processing patterns in line with business processes - for example, integrating telephony with CRM - leads to optimization of the sales process as a whole.

How IP telephony works

VoIP communication differs from classic analogue telephony. It converts a person's voice into digital packets rather than electrical signals. And this gives the business flexible options for processing requests.

The company receives multi-channel IP numbers from the provider. A virtual PBX can receive up to 100 calls to such a number simultaneously. She selects the recipient of the call, taking into account various factors: from the client’s location to previous communication experience. The simplest example: if the call comes from unknown number, IP equipment will forward it to the sales manager. If the call comes from a company partner, then IP telephony in the office will connect him with a specialist “leading” a certain direction.

By connecting IP telephony, you can listen to all employee conversations and identify errors. A reward system based on service quality increases conversion and improves the company's business reputation. And when collaborating with a remote call center (outsourced), control office telephony will help establish a fair price for services.

Other IP telephony opportunities for business::

connection of electronic instruments: systems feedback, automatic call forms, virtual chats, bots and other things;

compatibility of IP technologies with corporate systems planning, accounting and management, including CRM;

simple integration of work with calls into ready-made solutions and individually developed programs.

Multichannel virtual number also allows you to add other participants to the conversation, delimiting their communication. It looks complicated, but this SIP telephony function is driven by the real needs of companies working with customer calls. If problems arise in a conversation with a client, the process is controlled by the department head or trainer. Only the company manager will hear his comments and recommendations. SIP lines allow you to control communications in real time, preventing conflicts and increasing sales efficiency.

Equipment for IP telephony

Corporate telephony may include different types of equipment. For digital calls, an IP device is usually used. It is compatible with various systems routing and network architectures, which makes it easier to connect. An alternative to it are computers, smartphones and workstations with special applications for calls. IP telephony easily connects with popular instant messengers, including Skype, WhatsApp and Viber, making it convenient for small businesses.

Instead of a digital IP phone, you can also use a classic analog device. It is connected through an IP gateway, which converts electrical signals into digital packets. This solution simplifies the updating of existing communications.

Sometimes an IP channel serves as an intermediary between two communication systems. Good example: forward the call to an employee working away from home or on a business trip. In this case, the conversation via IP is sent not to a landline device, but to mobile phone. In this case, the client does not even know about difficult path, which overcomes the signal. The connection is established in a split second.

Favorable cost of communications from UIS

Our company is a reliable IP telephony provider. We have been working in the field of digital communications for more than 18 years and are among the TOP-3 Russian market virtual PBX (according to IKSMEDIA). The UIS network stability indicator of 99.97% makes IP data transmission fast and high-quality. In a highly competitive environment, instant connection with the client and clear speech transmission are the keys to successful sales.

Using the latest software and hardware systems allows us to set up telephony in the office in less than a day. We cooperate with different enterprises: from small startups to financial institutions and industrial complexes and online stores on a nationwide scale.

By connecting IP telephony from UIS, you get a convenient and affordable solution for business. Connection cost virtual PBX starts from 590 rubles per month.

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VoIP technology implements tasks and solutions that would be more difficult or more expensive to implement using PSTN technology.

• Ability to transfer more than one phone call within a high-speed telephone connection. Therefore, VoIP technology is used as simple way to add an additional telephone line to your home or office.

• Properties such as

• conference,
• call forwarding,
• automatic redialing,
• calling number identification,

are provided for free or almost free, while traditional telecommunications companies usually charge for it.

• Secure calls, with a standardized protocol (such as SRTP). Most of the difficulties to enable secure telephone connections over traditional telephone lines, such as signal digitization, transmission digital signal, have already been solved within VoIP technology. It is only necessary to encrypt the signal and identify it for the existing data stream.

• Location independent. You only need an Internet connection to connect to a VoIP provider. For example, call center operators using VoIP phones can work from any office where there is an efficient, fast and stable Internet connection.

• Integration with others over the Internet is available, including video calling, messaging and data exchange during a call, audio conferencing, managing your address book, and getting information about whether other subscribers are available for a call.

• Additional telephony features - such as call routing, pop-ups, alternative GSM roaming and IVR implementation - are easier and cheaper to implement and integrate. The fact that the phone call is on the same data network as Personal Computer user, opens the way to many new possibilities.

Additionally: the ability to connect direct numbers in any country in the world (DID).

Mobile numbers

Encoding introduces an additional delay of about 15-45 ms, which arises for the following reasons:

• using a buffer to accumulate the signal and take into account the statistics of subsequent samples (algorithmic delay);
• mathematical transformations performed on a speech signal require processor time (computational latency).

A similar delay occurs when decoding speech on the other side.

Codec latency must be taken into account when calculating end-to-end delays (see ). In addition, complex encoding/decoding algorithms require more computational resources of the system.

An analysis of the quality of speech data transmission over the Internet carried out in various research groups shows that the main source of distortion, reduction in the quality and intelligibility of synthesized speech is an interruption in the flow of speech data caused by:

• loss of packets during transmission over the communication network;
• exceeding the permissible delivery time of a packet with voice data.

This requires solving the problem of optimizing network delays and creating speech compression algorithms that are resistant to packet losses (recovering lost packets).

Codecs

The voice compression algorithms used when transmitting over an IP network are quite diverse. Some practically do not compress the voice, leaving it at the level of pulse-code modulation (that is, 64 kilobits per second), other codecs allow you to compress the digital voice stream by 8 times or more due to effective encoding algorithms. There are many good free codecs, the use of which does not require licensing. For others, it is necessary to achieve the appropriate licensing certification between the hardware (software) manufacturer and the authors of the compression method.

Codec Transmission speed, kbit/s Algorithmic delay, milliseconds Occupied stream, kbit/s IP packets Ethernet frames G.711 160 64 20 64,8 80 G.723.1 (6.3) 24 6,3 37,5 6,9 17,1 G.723.1 (5.3) 20 5,3 37,5 5,9 16 G.726-32 160 32 20 32,8 42,7 G.726-24 160 24 20 24,8 34,7 G.726-16 160 16 20 16,8 26,7 G.729 (8) 20 8 25 8,8 18,7 G.729 (6.4) 16 6,4 25 7,2 17,1 Network latency optimization The main advantages of IP telephony are reduced bandwidth requirements, which is ensured by taking into account the statistical characteristics of voice traffic: blocking the transmission of pauses (dialogue, syllabic, semantic, etc.), which can account for up to 40-50% of the time the transmission channel is occupied (VAD); high redundancy of the speech signal and its compression (without loss of quality during restoration) to the level of 20-40% of the original signal (see audio codec). At the same time, packet delays in the network are critical for VoIP, although the technology has some tolerance (resilience) to the loss of individual packets. Thus, the loss of up to 5% of packets does not lead to a deterioration in speech intelligibility. When transmitting telephone traffic using VoIP technology, the strict requirements of the ISO 9000 standard for quality of services must be taken into account, characterizing: quality of connection establishment, determined mainly by the speed of connection establishment, connection quality, measured by end-to-end (user-perceived) delays and perceived speech quality. The general acceptable delay according to the standard is no more than 250 milliseconds. The reasons for delays in the transmission of voice data over an IP network are largely related to the characteristics of packet transport. The TCP protocol provides packet delivery control, but is quite slow and therefore not used for voice transmission. UDP sends packets quickly, but recovery of lost data is not guaranteed, resulting in lost parts of the conversation when the audio is reconstructed (reconverted). Jitter (deviations in the period of packet arrival and reception), which appears when transmitting through a large number of nodes in a loaded IP network, brings considerable problems. Insufficiently high network bandwidth (for example, with simultaneous load by several users) seriously affects not only delays (that is, an increase in jitter), but also leads to large packet losses To solve such problems, a set of measures is proposed: use of algorithmic restoration of lost parts of the voice (averaging over neighboring data) prioritizing traffic during transport in one network by marking IP packets in the Type of Service field using a variable jitter buffer of the required length, which allows packets to be accumulated and issued again at normal intervals disabling media data proxying at a network bottleneck, that is, achieving direct speech exchange between the calling and called subscriber node through intermediate servers only at the stage of establishing and ending the call use of codecs with lower algorithmic latency (to reduce the load on the processor that implements the ADC and DAC) Connection security Most VoIP customers do not yet support cryptographic encryption, even though having a secure phone connection is much easier to implement with VoIP technology than with traditional phone lines. As a result, using a traffic analyzer, it is relatively easy to monitor VoIP calls, and with some tricks, even change their content. An intruder using a network packet sniffer has the ability to intercept VoIP calls if the user is not within a secure VPN. This security vulnerability can lead to denial of service attacks on the user or someone whose number belongs to the same network. These denials of service can completely destroy a telephone network, overwhelming it with junk traffic, creating a constant busy signal and increasing the number of caller disconnections. However this problem This also applies to traditional telephony, since there are no absolutely secure methods of communication. Consumers can secure their network by limiting access to virtual local network data, hiding your network with voice data from users. If the consumer supports a secure and properly configured gateway gateway with controlled access, this will protect yourself from most hacker attacks. There are several open source resources ( open source solutions), which analyze the traffic of VoIP conversations. Low levels of security are provided by proprietary audio codecs that cannot be found on open source lists, but this “security through obscurity” has not proven to be effective in other areas. Some vendors also use compression to make it more difficult to intercept information. It is believed that true network security requires full cryptographic encryption and cryptographic authentication, which are not available to the general consumer. However, in some respects, IP telephony outperforms traditional telephony in terms of security. The current security standard SRTP and the new ZRTP protocol are available on some models of IP phones (Cisco, SNOM), analog telephone adapters (Analog Telephone Adapters, ATAs), gateways, as well as on various softphones. You can use IPsec to secure P2P VoIP by using opportunistic encryption. Skype does not use SRTP, but it does use an encryption system that is transparent to the Skype provider. The Voice VPN solution (which is a combination of VoIP and Virtual Private Network technology) provides the ability to create a secure voice connection for VoIP networks within a company by applying IPSec encryption to the digitized voice data stream. It is also possible to perform multi-level encryption and complete anonymization of all VoIP traffic (voice, video, service information, etc.) using the I2P network, a router program for working with which can be installed on a PC, smartphone, netbook, laptop, etc. d. This network is a completely decentralized, anonymous data transmission medium, where each data packet is subject to four-level encryption using various encryption algorithms with maximum dimensions key An I2P network uses tunnel data transmission, where incoming and outgoing traffic go through different tunnels, each of which is encrypted with different keys, and the tunnels are periodically rebuilt with changing encryption keys. All this leads to the inability to listen and analyze the passing stream by a third party. At the same time, tunneling and encryption do not affect streaming, since a library specially created for streaming services is used, so the data arrives strictly in the given order, without losses or duplications. Caller ID Caller ID support may vary between providers, although most VoIP providers now offer a named Caller ID service for outgoing calls. When a call is made to a local network number from a VoIP provider, the caller ID service is not supported. In some cases, VoIP providers may allow a caller to spoof a caller ID that is not theirs, potentially allowing them to display an ID that is not actually the caller's number. Commercial VoIP equipment and software usually makes it easy to change the caller ID information. While this service can provide enormous flexibility, it also opens up the potential for abuse. Traffic statistics Any VoIP connection has a number of parameters that are generally accepted as accurate indicators of assessing the quality of the connection. In addition, most existing IP telephony operators, when providing services, even allow you to select the node through which the call will pass, not only based on price, but also on additional statistical parameters characterizing the quality of communication: ASR/ABR - the ratio of the number of calls served to the number of attempts to call as a percentage. Characterizes the best dialing. ACD - average duration of calls through a node to a given direction; % - the percentage of completed calls with a duration of less than 30 seconds. Characterizes the most stable connection during a conversation. Sometimes telecom operators also use other statistical parameters to evaluate the direction: Erlang, post-dial delay (PDD), percentage of packet loss (QoS), maximum increase in calls per second (Calls per seconds, CPS). The IP telephony station/server records detailed information about each specific call in the form of CDR records (call detailed records). Each record contains the number of the caller (A-number) and the called person (B-number), subscribers, IP addresses (or domain names), the time and duration of the call, and the initiator and reason for termination. Detailed records of calls (Call Detail Record), often uploaded to the billing system for analysis and subsequent blocking account caller, if necessary, call authorization (RADIUS). This verification method is usually typical for postpaid payment systems. Online accounting in billing is also used through the Accounting procedure in the RADIUS protocol, which is convenient in prepaid payment systems. Notes see also Links Monitoring and Debugging VoIP Networks Using a Network Analyzer Attack on VoIP: Interception and Eavesdropping “Chronic diseases” VoIP (online presentation, 16 min)

Calls to other cities and abroad using traditional telephone lines are not cheap. In addition, there are often cases when subscribers received bills for tens of thousands of rubles for conversations that they did not conduct. Connect to someone else's subscriber line is not particularly difficult even for a non-communication specialist... Is it really possible? the only way to protect yourself from the need to pay for someone else’s chatter is to disable the possibility of automatic long-distance and international communications(“G8”) and deprive yourself of the opportunity to call outside your locality? Of course, this is not an option. The solution to the problem is IP telephony (that is, Internet Protocol telephony). By turning off G8, you will leave no chance for attackers to talk at your expense, and you will be able to call to any city and country, and at very low rates.

Advantages and disadvantages of IP telephony

Let us highlight two main advantages of IP telephony over traditional telephone communication:

• The cost of calls is significantly lower
• You can turn off the "eight" and conversations strangers will be excluded at your expense.

A special case: in Moscow, calls between numbers in the codes “495” and “499” are made through “8”. Despite the fact that you disable your intercity access, the “eight” will still work, but only for calls between these codes. IP telephony has disadvantages over traditional telephone communication via “8”, but they are not so significant:

• When receiving an incoming call coming from an IP telephony network on a phone equipped with caller ID, it will be determined that it is not yours. subscriber number, and the dial-up number to the IP-telephony gateway, a random sequence of numbers or no number at all will be determined. If the subscriber you are calling uses the “white list” service (you can only reach him from certain numbers), then you will not be able to get through
• When using IP-telephony using cards (for information on types of IP-telephony, see below), you need to dial, in addition to the number of the called subscriber, the card number and its PIN code
• To use an IP softphone, you need to turn on your computer, download this program and connect a microphone and headphones
• Hardware IP phones require configuration for a specific Internet provider

Types of IP telephony

There are two main types of IP telephony.

• IP telephony using cards. To use it, you need a telephone with touch tone dialing, and there must be a provider in your locality that provides such a service. You buy a card, dial phone number IP telephony gateway, switch the phone to tone mode and then dial the card number, its PIN code and the number of the called subscriber with the country and city code. In this case, you do not need a computer or Internet access. You pay for long-distance calls according to the tariffs of your IP telephony provider and, if your city telephone network accepts time-based payment telephone conversations, the time of connection via your city telephone network with the IP telephony server (like a regular conversation around the city). Your conversation to the IP telephony gateway goes like a regular telephone network signal, is converted into a data stream on the server and sent over the Internet to its destination. There, at the so-called landing node, it is converted back into a regular telephone network signal and goes to the subscriber you are calling. In this way, you can call another city and country from your business phone (a blocked “8” will not be a hindrance for you), with cell phone, from the phone, for example, of your friends or relatives who you are visiting, or from the phone of a hotel room. In all cases, this will be a regular call within the city, and for long distance communication the money will be debited from your card, no bills will be received.
• Conversation using special IP phones. In this case, you must have access to the Internet, but it is not necessary to have a telephone line and an IP telephony provider in your city.

IP phones can be software (they are a program installed on a computer, for example, X-Lite is free, you can download it) and hardware (they look like regular phones). Softphones require headphones and a microphone to be connected to the computer, and in order to receive calls, the computer must be turned on and the program must be running. Hardware IP phones are equipped with a handset, a computer is only needed to configure them, and they work regardless of whether the computer is turned on or whether there is one at all. Some hardware IP phones (for example, Planet VIP-155 PT) can be configured without a computer.

Currently, there are many models of hardware IP phones. For their operation, an Internet channel and a 220 V power supply are required. A telephone line is not needed. It also does not matter how the Internet is accessed - via a local wired network, an ADSL channel (the modem must be equipped with an Ethernet connector) or through a wireless provider (in Moscow - Golden Wi-Fi), to which using a special wireless adapter(for example, Zyxel P-330W EE) you can connect equipment with an Ethernet connector. You cannot connect a hardware IP phone to a regular telephone network. Although there are models that can work both as IP phones and as regular devices for city telephone networks.

How does an IP phone work?

An IP phone (a separate device or a program on a computer) converts your voice into a stream sound files, which are transmitted over the Internet. If you call a computer or hardware IP phone, this stream is converted to your voice directly on the computer or hardware IP phone you are calling. If you call a regular wired or cell phone, then at a special communication center the stream of files from the Internet is converted into an electrical signal that is transmitted over wires or through cellular network to the subscriber you are calling, and in his phone this signal turns into your voice. Herein lies the secret of the low cost of IP telephony: your conversations can be transmitted in a denser stream than when using traditional telephone communication. After all, you can transmit more data per unit of time with the same channel capacity!

Skype or SIPNET?

To make calls using an IP phone, you need to become a subscriber to one of the IP telephony networks. Such networks are like common use, to which anyone can connect, as well as closed ones, intended mainly for corporate communications and available only to a limited number of persons ( office PBXs, connection of remote units with the central office). Closed networks, although they operate using the IP protocol, are not connected to the Internet at all. In this article we will only refer to public networks.

There are many such networks. The most famous of them is Skype. Conversations between its subscribers are free regardless of their location, and a small fee is charged for calls between Skype and regular telephone networks (Skypeout service). And here is where the disadvantage of this network emerges: you can pay for this service either with certain types of bank cards or with Internet money. Not everyone has bank cards, and not everyone will like the need to create an electronic wallet and register in an online payment system. In addition, Skype is aimed mainly at soft IP phones, and a handset-terminal connected to a computer via USB (for example, Trendnet TVP-SP3) does not work if the computer is turned off.

Another network that deserves our attention is SIPNET (www.sipnet.ru). The Sip protocol used in it is similar to Skype, but is incompatible with it. That is, it is impossible to call a Skype subscriber from the SIPNET network and vice versa, even for money. Of course, you can use the Skypeout service and call a local SIPNET dial-up number, but direct communication there will be no more between these networks. You can't call other Sip networks either. Just like Skype, you can also make video calls when using SIPNET.

Calls between SIPNET network subscribers are free. For calls from the SIPNET network to a regular landline or cell phone, you need to pay a small amount. That is, in this sense it is similar to Skype. But when using SIPNET, you can deposit money in rubles both through payment machines and through the cash desks of many communication stores. Use bank cards and Internet money to pay for SIPNET services is possible, but not necessary. So, in terms of paying for communication services, SIPNET is much more convenient than Skype.

Most hardware IP phones work with the SIP protocol. They are more convenient than software ones, since they work independently of a computer, and anyone who knows how to use them can make calls regular phone. The question arises: is it possible to call these phones from regular landline phones? If you use a SIPNET network, then you can. But not in all cities. In Russia, such an opportunity exists in Moscow, St. Petersburg, Omsk, Nizhny Novgorod, Kazan, Yekaterinburg and several other cities, full list which you can find out in help desk SIPNET. To make a call you need a telephone with tone dialing. The cost of the call will be debited from your personal account on the SIPNET network.

The union of SIPNET and Sky Link networks saves your money!

Since an IP phone generates only Internet traffic during a conversation, to optimize costs, we recommend that you connect to the Sky Link tariff, intended for active Internet users. Keep in mind that when using an IP phone, Sky Link charges you only for Internet access; you do not pay for voice services over this network, since you do not use them. And the fee for voice transmission is charged by the IP telephony operator (SIPNET) and only if you call a landline or cell phone.

Thus, the cost of a call on an IP telephone through the Sky Link network will consist of the sum of the cost of Internet access and the cost of using IP telephony services, but in the end it will still be cheaper than using traditional long-distance and especially international telephone communications (calls via IP telephony to many countries in Europe, North and South America is 20 times cheaper than via regular telephone networks).

As we already said, you can accept incoming phone calls to your IP phone both from other IP phones and from regular landline (with tone dialing) or cell phones via special number access. Please note that subscribers calling you must dial the number assigned to you by the SIPNET network (the so-called SIP ID), and not the subscriber number assigned to your RUIM card in the Sky Link network, since, we repeat, you use Sky Link only for data transmission. And therefore, it makes no sense to purchase a direct landline or “beautiful” number from this network. Incoming calls are free for you, and those calling you from a landline or cell phone pay for the conversation with you at the rates of their telecom operator for calls to landline numbers. You can connect to the Sky Link network and pay for its services without commission in any of our stores.

Verdict ION

Which method of using IP telephony is better: using cards or using IP phones? There is no clear answer to this question. It would seem that the “card” method is simpler, since you buy a card and call, you only need a phone, and you can put up with the need to dial a large number of numbers. This is, of course, true, but... It happens that there is no telephone line in the room at all, but the signal from the Sky Link or Golden Wi-Fi network is “caught”. This means that you will be able to use IP telephony, and you do not need to lay any telephone lines. But not “card” telephony, since without a telephone line you cannot talk on it. In addition, if your interlocutor is a SIPNET subscriber, you can talk for free for as long as you like, even with Australia or South America. And the “card” IP telephony operator will never give you the opportunity to talk for free. Even if phone line is, then when paying for calls by time, you need, in addition to the IP telephony itself using cards, to pay for the time of connection with the “card” server over the local telephone network. So each method is good depending on the specific situation.

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Communication with other cities and countries costs a pretty penny. VOIP (IP telephony) allows you to communicate with anywhere in the world at affordable rates. What it is and how it works is not necessary for dummies to know. It is important to be able to apply innovation.

Besides, Lately Cases have become more frequent when subscribers of traditional networks receive bills of incredible sizes for services that they did not use. To avoid such incidents, you can completely disable the option long distance communication and leave yourself without communication.

Telephone conversations carried out via the Internet protocol allow you to protect yourself from attacks by intruders and not limit your communication.

Why companies around the world are switching to IP telephony

Features of VOIP (IP telephony)

This type of communication appeared relatively recently. And today it is gaining more and more fans.

What it is

Subscribers are connected via the Internet using various protocols. For dummies, the details of organizing services are not needed. The main thing is that the connection is of high quality and inexpensive. Let us only note that two main protocols are currently used:

• SIP - the most popular, ensures user mobility while maintaining their number;
• IAX2 - provides more reliable and high-quality communications, but is more complex to organize and has weak protection against hacker attacks.

The use of modern protocols can significantly save traffic; they can be used to support different mobile devices, applications.

Their users receive the following benefits:

• making voice calls;
• connecting subscribers using video communication;
• transmission of multimedia information, exchange of various files;
• correspondence via text messages;
• the ability to play online games.

Subscribers communicate via the Internet. Calls to landline numbers telephones are carried out using special gateways.

The majority of VOIP (IP telephony) operators provide services using SIP, since it is easier to maintain and organize services.

Benefits from IP telephony

How the connection works

The specifics of using protocols are often not of interest to ordinary users of such services. For dummies, we’ll explain how communication works in layman’s terms. Let’s analyze the algorithm for connecting two subscribers in the most accessible way possible:

1. At rest, both devices must be connected to the Internet and maintain a connection with the selected operators.
2. When the first subscriber dials the internal number of the second, the servers find his location and send him a signal.
3. If the second party accepts the call, the connection will be established.

Communication is carried out via the Internet; traditional telephone networks are not involved here. Therefore, charging is carried out based on the traffic spent.

How IP telephony works

How much do Internet telephony services cost?

Seeing an unfamiliar abbreviation and unusual terms, most users are lost, not understanding what it is. However, communication via the Internet is becoming more and more popular; millions of subscribers already use it every day.

To save money and enjoy such services, you must be a subscriber to one of the IP operators. Interestingly, communication with subscribers of one provider is not charged. Interlocutors only need to pay for the traffic spent on the connection.

Thus, if you have unlimited Internet and the phone is connected to the Internet via Wi-Fi, calls will be absolutely free.

Tariffs for international calls are also much lower than those of traditional telephone network operators. The cost of a regular connection depends on the distance between subscribers. Since distance is not of fundamental importance for the Internet, international tariffs for connecting to subscribers outside of one provider seem negligible.

To select equipment, you need to answer several questions for yourself.

Popular SIP operators

To communicate using an IP phone, you must become a subscriber to any IP telephony operator. Such networks are either public, to which anyone can connect, or closed, intended, most often, for corporate communications, accessible exclusively to a limited number of subscribers (office PBXs, communication between remote departments and the central office). Such closed networks, although they operate over the IP protocol, may not be connected to the Internet at all. Therefore, we will talk exclusively about public networks.

Today there are a large number of networks using IP telephony. The most famous is Skype. Communication between network subscribers is free, regardless of their distance from each other. Communication between users of Skype and traditional telephone networks is also insignificant compared to the tariffs of conventional PBXs (Skypeout service). The only drawback of the operator is the ability to pay for services exclusively with electronic money and certain types of bank cards.

SIPNET is a similar network that deserves the attention of subscribers. The protocol that is used to communicate with its users is similar to Skype, but is incompatible with it. That is, users of two different operators cannot contact each other even for money.

The most popular IP telephony functions

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