IP telephony without being tied to a provider. How to connect IP-telephony

Intercity and international calls over "traditional" telephone lines is a real luxury for most of the inhabitants of our country. high price and low quality connections make more and more users refuse to communicate with relatives and friends from other regions. Moreover, the insecurity of the telephone line makes it an easy target for intruders - with the proper ability to connect to it and talk at your expense, anyone can.

If you do not want to put yourself at risk of being robbed, but still cannot refuse "international communication", you should think about connecting IP-telephony. What are Internet calls, what are the advantages of the system and how to set up a connection - we will try to figure it out.

Digital calls

IP telephony is a combination of old habits and modern technologies. This is a set of communication protocols and methods that provide traditional dialing and two-way communication over the Internet and any other IP networks.

Unlike conventional, fixed phones, in which the voice of the interlocutor is transmitted by an analog signal, in IP telephony, sound is encrypted in binary code and compressed. This improves the quality of communication and reduces the load on the network. Other benefits of calling over IP telephony are:

1. Low cost of international and long distance calls.
2. Independence from telephone lines.
3. Making calls anywhere.

As a last advantage, we should highlight the possibility of blocking unwanted incoming calls at your expense by disabling the G8. Using IP-telephony is profitable and convenient, but, like everything new, you need to get used to it.

Types of IP telephony

Internet calls can be made from a regular landline phone, from special IP equipment, and even from a computer.

According to the type of device through which communication is carried out, there is a division of IP telephony for the home into types:

1. "computer-computer". To communicate, subscribers need a PC with installed software and an Internet connection. The call in this case is similar to communication in Skype. This type of connection is the least common.
2. Communication through the map. To make a call, you need a regular landline phone with tone dialing and an access card from the provider. To contact a friend, you first call the operator's number, enter your ID and PIN code in tone mode, and then the number of the called subscriber.
3. Communication via IP phone. A special IP phone is already configured for communication. All you need is an Internet connection. When you make a call, the phone automatically connects you to the provider, connects to the proxy server and calls the subscriber.

Many probably have a question: what is an IP phone? It is a conventional device with a handset and a keyboard, works independently of a computer and can receive a call at any time.

Foreign operators in Russia

Choosing a provider becomes the first step towards communication through IP-telephony. The cost of calls will depend on the choice made, so choose a service company, considering the pros and cons. The largest representatives of IP-telephony in our country are Sipnet and Comtube.

Sipnet is one of the first foreign companies to set up a representative office in Russia. Its services are ideal for making calls within the network, that is, for communicating with citywide numbers - calls are completely free. For other directions, the tariffs for IP-telephony are as follows:

• international calls - from 1.5 to 6 rubles / min;
• intercity communication - up to 1 rub / min.

Reviews about the operator are positive. Some are confused which is held in English.

Comtube is one of the youngest and most promising providers. It provides its customers with two sets of services - "Starting" and "Premium". The first set will provide customers with basic capabilities, and the second, among other things, will provide a range of additional services. The cost of calls depends on the terms of the contract.

It is impossible to give reliable reviews about this operator - too few users are familiar with it. Some are happy with the quality of communication and a fairly wide range of options in the Starter package, others complain that all the service is fixated on VIPs.

Domestic providers

Zebra Telecom is one of the most promising providers in Russia. Provides customers with the opportunity to call both using an access card, and through a PC and an IP phone. Calls from "Zebra" to "Zebra" are absolutely free. Long-distance calls cost from 50 kopecks / min, international - from 1.5 rubles - it all depends on the country of the subscriber.

Among the positive qualities, it is worth noting the Russian-language localization software. According to customer reviews, this is one of the many advantages of a domestic provider.

IP-telephony from Rostelecom will be a profitable solution for those who need constant communication with subscribers from other countries. Unlike other operators, which have per-minute billing for calls, with Rostelecom you pay for minute packages once a month or as the traffic is used up.

So, the cost of a package of 100 "international" minutes will be about 250-300 rubles. It does not matter which country you are calling. But for some clients it will be more prudent to use per-minute billing, especially if you talk to "abroad" for less than 50 minutes a month.

Necessary equipment

The set of equipment necessary for communication does not depend on the chosen telecom operator, but on the preferred type of IP telephony. So, for computer-to-computer calls, you will need an Internet access point - a fiber optic cable, a USB modem and equipment for comfortable communication: a microphone, headphones, for video calls - a webcam.

To call IP-telephony numbers from a landline phone, you will need a SIP adapter and a computer or a router with a built-in IP gateway. If you are using hardware IP phone, then you will not need anything other than himself.

Setting up communication via adapter

When choosing an operator, ask what kind of equipment is needed to connect to a leased line, is it easy to buy and is it expensive.

Some providers offer their customers already fully configured adapters for communicating with other subscribers. In this case, the entire configuration process comes down to the sequential execution of several steps:

1. Using the instructions, connect the adapter to the network.
2. Connect a fixed line telephone to the LINE1 slot using a standard
3. Turn on the adapter by inserting the power supply into the socket, wait for the download to finish (2-3 minutes).
4. Pick up the phone, wait for the tone.

As soon as you hear a tone signal on the other side of the line, then know that you figured out what IP telephony is and were able to connect the equipment correctly. Now there are no barriers to communication.

Setting up some softphones

Setting up IP phones has some peculiarities. In particular, you will need to program your device and enter information about yourself into its database. This is not as difficult to do as it seems.

Before proceeding with the setup, make sure you have an ID (identifier), as well as a passphrase or PIN. Here is an example of the data that most phones require when connecting to a Sipnet operator.

Other operators should have a similar procedure for setting up IP telephony. Customer reviews report that it is easy to deal with it. In addition, in case of problems, you can contact the operator. Helping you with the setup is their responsibility.

Disadvantages of IP telephony

Now that you have learned the basic principles of connection, the advantages and technology of Internet telephony, you are ready to learn about some of the disadvantages of this method of communication. Such information will help you decide whether you need IP-telephony or not.

The first and one of the most significant disadvantages is the dependence on the power grid. If you use a PC or a landline phone to communicate, then “without light” it will be impossible to get through to you, as well as you yourself to make calls. The exception is hardware IP phones.

When making a call for the first time, the interlocutor most likely does not recognize you. It's all about the caller ID - the caller's display will show the number of the gateway to which you are connected, and not your own.

The last and one of the most important drawbacks is the high price of the equipment. Many customers are at a loss that such an IP phone can cost up to 3-4 thousand rubles, and this is without subscription fee. However, by installing it in your apartment, you can no longer think about prices when communicating with subscribers from other countries.

Modern society is increasingly refusing the services of telephone companies, because this type of communication is distinguished by the high cost of calls, especially long-distance calls. Adherents of traditional telephone communication remained only in areas not spoiled by civilization. With the development of Internet services, telephone lines have lost their relevance, and they have been replaced by more practical ways of communicating and exchanging data. You can make calls regardless of your location if your device has a built-in wifi receiver waves. You just need to find and make a call. The ability to use communication via the Internet without additional expenses is provided to any owner of a suitable device.

IP-telephony is a relatively young type of communication, the rapidly growing popularity of which is due to comfort along with low cost. Even if there is no IP-telephony provider in your city, you have the opportunity to connect an IP-telephone and use communication via the Internet. In this case, you need to access the network in any way, be it local connection, using a modem or Wi-Fi router, and no additional telephone wire connections are needed.

An IP phone can be software or hardware. In any of the options chosen, it does not matter how the connection to the network is made.

• A software IP phone is an application installed on a computer, such as the well-known Skype. To make calls, you must have a headset, access to the Internet, and the computer and the program must be running.
• A hardware IP phone looks similar to a regular one, equipped with a handset. If you purchased a phone with a built-in Wi-Fi receiver, you do not need to turn on your computer to use the connection. A PC will only be needed to set up the IP phone. Some models can be configured even without a computer.

Connecting to IP Telephony

You can choose any of the connection methods based on your financial capabilities and the requirements for such a communication tool. A minimum cost will be required to use a software connection, since the purchase of a special device is not required if there are already devices that support this communication format.

Software connection with headset

In case of connection programmatically you simply download and install on a computer or other device the selected application that communicates via the IP protocol. For the most part, such programs are free and freely available, and their configuration does not take much time. You need to create an account for the selected application, enter the necessary data, during installation the parameters necessary for operation are set by default, in the future you can make your own adjustments to the settings. To make calls and video calls, you must have a headset, external or built into the device. In addition to computers and laptops, you can also use tablets or mobile phones. Modern devices, with a Wi-Fi receiver, have the ability to use such programs for calls.

USB devices

You can make calls by turning on the IP phone in USB port your computer. Of course, you need to set it up first. Instructions for each model will be different, it is always attached. You can obtain the necessary network setup data to be entered from your ISP. Like any connected external device, the system must detect it. Drivers suitable for your phone will help to synchronize the operation of both devices, they are usually included in the kit.

Options appearance such a USB phone:

• mobile phone with USB cable;
• landline phone;
• wireless radiotelephone.

When you connect such a phone on your computer, you need to run an application that communicates via IP protocol. For the program, the correct operation must first be configured. Some software vendors offer for sale customized specific application devices, such as wired Skype handsets, but you can set up synchronization with the program on any phone, then it will not matter whether your computer is turned on or not to make calls. Fixed and cordless telephones can be successfully used at home or in the office. It is very convenient to connect USB handsets when the user is often on the road and connects to the network via Wi-Fi.

SIP adapter

An inexpensive and practical way to connect using an adapter is when you have a Wi-Fi router, as an independent device, or built directly into the adapter itself. Both a computer and an adapter are connected to the router using USB ports. The network cable must be connected to the router, regardless of whether it is built-in or not. The IP phone must be connected to the adapter, and the tone dialing mode must be set in the menu. Thus, there is no need to turn on the computer in this connection option. Different SIP adapters can support from one to several accounts at the same time.

SIP devices

This is the most comfortable, but also, accordingly, the most expensive way to connect. Diversity model range devices are very large. An IP phone can be equipped with a Wi-Fi receiver, a screen for video communication, and a built-in router. Some models have the ability to connect to several SIP servers, then you can make and receive calls by choosing the most suitable one. In the case when the IP phone is already equipped with a router, then network cable connects to it, and the computer to the phone. When you connect the Internet to the phone, neither a PC nor a laptop is needed for its operation.

Setting up IP telephony

So, regardless of which device you have chosen and which provider you are connected to, there is general principle settings, which is applicable for any IP phone, you will find more detailed details on setting up the functionality of a particular model in the instructions that come with the device.

Before purchasing the machine, check with your ISP to find out which equipment will be most compatible with its network. It is possible that the operator already has customized adapters or devices for sale, then connecting the device yourself will not be difficult.

When you connect all the necessary wires directly from the phone to the computer or to the adapter, turn on the device and wait for the download. Pick up the handset and wait until the dial tone appears. An IP phone equipped with a Wi-Fi handset or router (or if connected directly to it) can work without a computer.

The presence of an IP phone implies the ability to always be in touch, if necessary, you can set up call forwarding in the menu. The communication protocol used in IP telephony allows you to communicate with different subscribers by converting the signal. You can make calls to mobiles, landlines even to the other side of the world, while the cost of using communication is minimal.

IP-telephony is a telephone communication over the Internet channels, and not over the usual telephone networks. This type telephony became possible as soon as the web of the Internet became comparable and even larger than the web of telephone lines that entangled the Earth long before the Internet.

The difference between IP-telephony and analog is the absence of a traditional cable and telephone. True, there are options for IP telephony that are outwardly indistinguishable from the usual telephone communication, with familiar devices and wires. Communication is carried out through devices that have direct access to the Internet. It can be not only computers, but also tablets or mobile devices. An audio headset is also required if the computer does not have speakers and a microphone.

The main advantage is the minimum cost of operation, the cost of paying for calls, in comparison with analog telephony or cellular communication.

This telephony is especially popular in offices, opening up opportunities for significant cost savings. After all, office workers only do what they call the company's customers, contractors and for other reasons.

It is important that communication costs are reduced regardless of which region of the country or another state is connected, because for the Internet, unlike conventional telephone communication, there are no state and national borders. Ease of configuration and a sufficient level of security enable IP telephony to compete with analog telephony, gradually replacing it with corporate needs.

At the household level, IP-telephony at one time was quite widespread in the form of cards for intercity and international communications.

Having bought such a card for relatively little money, from a regular home phone, access was opened to the servers of a company that provides access to IP telephony. Numbers for dialing to servers were published on the card, and then, according to the usual rules for dialing long-distance or international number it was possible to call another subscriber, but already through Internet channels, and not through a telephone line. A phone line was used in this case at the cheapest rate: in the area between the telephones of speaking subscribers and servers located in the same cities and countries to provide IP telephony.

Basic principles of how IP telephony works

When making a call, the voice signal coming from the subscriber is compressed and converted into a data packet sent via IP networks. Getting to the address of the recipient, the transmitted information is decoded back, acquiring the format of a familiar voice signal. All this happens in a matter of fractions of a second, thanks to which information is transmitted in real time without loss of broadcast quality.

Contribute to such a positive result protocols that act as a kind of encrypted language that unites subscribers and allows you to transfer data to each other. IP-telephony is implemented on the basis of several of the most popular types of protocols.

Connecting and configuring IP telephony

To use the technology, appropriate equipment is also required for this: routers, routers, servers, etc.

A software connection to IP telephony consists in installing a laptop or gadget of the appropriate application that communicates over a protocol that ensures the operation of IP telephony.

The software is mostly free. To use it, you need an account in the application, in which the data required for work is entered. A set of basic functions is installed by default, it is possible to expand them, make adjustments to the settings.

The history of the emergence of IP-telephony

It became possible to transfer audio and video files, text messages over the Internet using ISDN. But this program did not find a response, as it worked very slowly and until 1995 there were no innovative developments in this direction.

Then came the first sample of Internet telephony from the Israeli company VocalTec. But he worked one-sidedly, according to the principle of walkie-talkies, requiring identical software from users, between whom communication was carried out. Also at that time, it was quite common for data to be lost during transmission, mainly due to the low speed of the Internet at that time.

To modern achievements of IP-telephony

Until 1996, IP-telephony developed on the principle of transferring information from computer to computer using communicator programs. But in 1997 there was an integration telephone networks with so-called "packet" networks, in fact with Internet networks, which became possible due to the adoption of the standard H323 data transfer protocol.

Based on this protocol, the first phones began to work, equipped with a special connector for connecting to a data network and requiring not only a telephone socket, but also a separate port. When the switch was overloaded, it took time to rebuild it, which for a long time led to a loss of interest in this direction.

Changes occurred in 2002, when, with the development of the popularity of the new SIP protocol, which appeared back in 1999, packet telephony began to be actively introduced. After another 3 years, with the help of a new router, VoIP became possible job telephony without turning on the computer at all.

Since then, the popularity of IP-telephony has been constantly growing. For ordinary users, it does not matter what protocols are used and how they work. They are much more important than the purity of communication, additional features and low rates.

Benefits of IP telephony

The main one is the ability to save communication costs, which is especially important when using long-distance and international calls. Also, as advantages, it should be noted:

• Accessibility and mobility,

since numbers in IP telephony are not tied to a specific place, to a specific cable, to a specific connector.

Such essentially virtual number can be accessed regardless of the geography of the location, you only need high-speed access to the Internet. It turns out some kind of analogue mobile communications, but instead of accessing mobile networks Internet access required.

• High potential,

since the formation of new IP networks is carried out depending on the needs of users and it is possible to quickly expand the configurations with the introduction of new services.

• Privacy & Security.

Thanks to encrypted communication channels, access to information to third parties is closed, unlike the old familiar telephone networks, to which anyone can connect anywhere where the cable runs.

• Opportunities,

Using IP telephony - optimal solution for offices, enterprises and organizations precisely because of the last point about the possibilities.

• Functions multichannel number,
• forwarding incoming calls,
• voice mail,
• virtual fax and
• blacklisting service

allow you to get the most out of communication without any effort.

Most IP telephony services are included in basic package and are used after payment for the provider's services for such communication. It is possible to increase the number of rooms beyond the original tariff plan, but in this case, additional costs will be required.

About the cost of IP-telephony

When using VOIP-telephony, you can clearly see the striking difference in prices compared to analog communications. Within the network, calls are not charged, that is, subscribers using the services of one IP telephony provider communicate via software or hardware VOIP phones, saving cash.

Since traffic on the Internet is not geo-referenced, the distance between the region of sending and the region of receiving information also does not play a role, in contrast to the usual telephone connection, which operates on the principle "the farther, the more expensive." There is no additional fee for sending traffic to any direction.

When calling mobile or landline phones abroad or to other regions, the cost of expenses is also an order of magnitude lower than in an analog network. There is no subscription fee either, but the truth is, instead, you need to pay for Internet use at rates.

The cost of calls to mobile and landline phones depends on the chosen direction and starts from a few tens of kopecks per minute. The specific figure is related to the cost of the services of a provider that supports IP telephony. A company involved in setting up and connecting such a connection will help you choose the best package based on the needs of the customer. A combination of services from several providers is possible, which is guaranteed to lead to a decrease in bills for payment for communication services.

VoIP competitor: Skype

Applications for maintaining telephone and video communications quite successfully compete with IP telephony, for example, well. Similar applications for computers and mobile devices allow for voice and video communication between subscribers also via Internet channels, and also have attractive tariffs.

By the way, many functions of such applications are generally free. Users only need to pay for Internet traffic, nothing more. For example, Skype calls between two subscribers who have the Skype application installed on their computers are free.

And even group and Skype audio between multiple Skype subscribers can be free. It is also possible to transfer visual information by "sharing" (organizing collective viewing) of one of the screens of a computer connected to a Skype conference.

Competitors of IP-telephony: mobile operators

In addition, mobile operators do not stand still. They offer their to corporative clients the so-called virtual telephony. Its essence is that each employee of the corporation (firm) is assigned short number(3-4-digits) as if it were an employee's internal telephone number. And all employees of one company can call each other using these short numbers, but using mobile phones or special telephone sets connected directly to the company's servers providing Internet access.

A feature of mobile virtual telephony is that it does not link an employee to a workplace, to a specific city, or even to a specific country. The short number assigned to a company employee "travels" with him everywhere, along with a gadget and a SIM card. The result is a comparable in price analog of IP-telephony, which does not require anything from users (and companies) at all, except mobile phones(smartphones, iPhones) and SIM cards mobile operator.

Results

In general, progress does not stand still, and competition encourages manufacturers to find more and more convenient ways voice and video communication between employees of corporations and between ordinary people.

Yes, and "old" telephone companies do not stand still, developing their networks and transferring them "digitally" in search of competitive solutions that will allow them to successfully "compete" with IP-telephony.

IP telephony or Internet telephony is a communication with the transmission of voice information in digital form over the Internet. For data exchange in IP-telephony, many specialized protocols are used, designed specifically for working with voice, but the most popular of them is the SIP protocol. Therefore, when talking about Internet telephony, people often specify and call it SIP telephony.

Why IP telephony is so popular

Over the last 2 decades virtual telephony quickly gained popularity all over the world. Several factors contributed to this:

• The development of the Internet, increasing its quality and accessibility.
• More profitable international and international calls.
• Ease of implementation.
• No equipment is required to use PBX functionality.
• Availability additional features for business based on telephony (for example, automated analytics).
• Simplification of the use of functions that already existed in traditional telephony (for example, call recording, conditional redirect, voice menu).
• Non-attachment to a specific place (that is, you can call from anywhere in the world where there is Internet).
• As a consequence of the previous paragraph - the preservation of the number during any move.
• Easy scalability. In traditional telephony, scaling is usually associated with purchase. additional equipment. In Internet telephony, it is enough to simply switch to a more “advanced” tariff.

IP-telephony from New Tel

What is VoIP? What is the difference between VoIP and IP telephony?

IP telephony is a broader concept, because it includes, for example, also video communication, that is, the exchange of visual data. VoIP (Voice over IP) refers only to the exchange of voice data. Applied to telephone conversations, these terms often mean the same thing.

Example. Some modern IP phones have a video call feature. To say that such a video call is organized using IP telephony is correct, but to say that this is VoIP telephony is not entirely correct, because only sound is transmitted using VoIP technology in this call.

How to make calls using IP telephony

One of the significant advantages of IP telephony is the ability to use it with different devices, including at the same time.

Most often, three types of devices are used for calls:

IP Phones – The use of IP phones makes Internet telephony look like a traditional phone. With the difference that the setup is much more convenient and faster.

Mobile phone - can be used in two ways:
1. Using redirection. When a call arrives at your cloud PBX, it sort of “calls back” to your mobile and connects you to the caller. At the same time, you are talking using the usual connection of your mobile operator and not using the mobile Internet.
2. Using mobile application. To do this, you need to install the client program on your phone and log in. In this case, you will make calls via the Internet. In essence, this is very similar to audio calls via Skype or WhatsApp.

Personal Computer. To work with telephony in this case, you also need to install a special application. Usually the call itself is made using a headset. This scheme is often used in call centers, because allows you to make calls directly from CRM, having at hand all the necessary data about the client.

Additional features of virtual telephony

The functionality of IP telephony is not limited to audio calls. The technology provides the opportunity to introduce many additional "chips" that are either difficult to implement in traditional telephony or completely impossible. Here are some examples:

Redirects with a variety of conditions. For example, you can set up call forwarding by time: call a landline phone during business hours, and call a mobile phone during non-working hours. Or by incoming number: forward all calls with the Murmansk code to employee A, and from Moscow to employee B. Transfer if there is no answer: first call employee A, if he does not answer, then employee B. Forwarding can also include call interception (call transfer to your phone by pressing a certain key combination) or call transfer (transfer a call to another employee by pressing a certain key combination).

Recording of all conversations. Of course, this can also be implemented in traditional telephony. But with IP telephony, everything is much simpler - all records are stored in the cloud, they can be filtered by various parameters, such as date or employee.

Free communication within the network. Employees connected to the same network can call each other for free. And, since the call is made via the Internet, there is no difference whether these employees are in neighboring offices or in different countries.

WITH complete list New Tel IP telephony capabilities can be found.

The term "IP-telephony" usually means several types of telephony. We offer you a way to connect this service on your home computer.

The entire questionnaire is in Russian with clear explanations. You enter the necessary data, come up with a username and password for your account.

After that, launch the program itself, specify the newly registered login and password, and get into the main menu. This procedure does not cause any difficulties.

Assemble and install the machine in a convenient location and connect to the network, either directly through an RJ-45 Internet jack, or using the “computer>telephone>Internet network” scheme, as indicated below.

If the computer has a Wi-Fi module and works based on the 802.11 standard, that is, wireless technology, then the phone connects to WiFi router, by means of a patch cord with RJ-45 connectors crimped according to a certain pattern.

After plugging in the power cord, your phone will automatically start setting up the presets. Some companies customize phones before they sell them. If you are unlucky with the supplier, you will have to do it all yourself.

Find out the IP address of the phone that it received when it was connected to the network. To do this, press and hold the “OK” button. Enter the received address in the address bar of the browser on your computer. It is better that it be either the standard Explorer, Opera, Chrome or Mozilla. A window will open for entering a login and password, by default it is: admin / admin.

After logging in, you will see the main status tab of the Yealink product web client, which displays information about the phone, its software version, build number, network information, WAN port mode, WAN IP address, MAC address, network status, LAN IP address. address, device operation mode, and DHCP server status. For the average user this information has no particular value.

The next tab - "SIP account" - is already needed to enter the parameters. This phone can have two accounts, select one, for example the first one, which is set by default to call.

1. In the “Active line” item, put on, thereby turning on the account.
2. Display name and label - fill in at your discretion, this is the name of the line that will be displayed on the phone screen.
3. Fill in the identification name and account name according to the data provided by the SIP telephony service provider. These are, in fact, subscriber identification numbers, those by which the central server of the provider will search and connect with the user. The password must also be provided by the provider.
4. The provider's SIP server, its address and port are also provided by the provider.
5. If the provider reported using an Outbound server, then you need to turn it on and enter its IP address.
6. The default data transfer protocol is UDP, otherwise the provider must also report this.
7. Also, if an additional Outbound Proxy server is specified by the provider, its address must be entered in the active field.
8. If the provider's network uses a STUN server, you must specify it and enable Nat Traversal.
9. Voice mail it is possible not to specify, also not to change the values ​​of the anonymous call, and the rejection of the anonymous call.
10. The proxy server address is also reported, if necessary, by the provider.

All information must come from the provider or prescribed in the contract, or upon request to the service technical support. After entering the above data, click the "Confirm" button.

Close the web client and restart your phone by turning the power off for a minute and then on again. The SIP phone itself must configure itself according to the specified parameters and enter the network.

If the registration was successful, the account label will be displayed on the phone screen, and it will be possible to make calls from the number provided by the IP telephony provider.

As you can see, connecting a SIP phone to a computer for free at home is difficult, but possible. The main thing is to get a complete list of parameters from the provider. After that, carry out the configuration according to the above steps, and use the economical type of telephone communication - SIP-telephony.