SIP-telephony - what is it? Internet telephony (IP-telephony): reviews

In recent years, SIP telephony has become very popular. What is this communication standard? How do you configure the appropriate software and hardware solutions for correct use of it? In which cases is this connection more advantageous in comparison with the traditional one carried out through a regular phone? Now we will study these and other aspects.

Terminology

SIP-telephony - what is it? What are the distinguishing features of this technology? IP-telephony - is it the same? Everything depends on the methodology of classification of communication standards, which we take as a basis. There are four of them today.

According to the first, SIP- and IP-telephony - subcategories of a more global concept. What kind? Some experts call it "Internet telephony", others - "VoIP technology", from voice over IP - voice over IP, Internet protocol. IP-telephony has, based on this concept, a distinctive feature - the closeness of communication technologies. In turn, the SIP connection is based on open connection protocols.

The second methodology implies that SIP-connection is a particular variant of a more capacious concept, which is IP-telephony. In turn, if we are talking about closed connection protocols, they are usually called based on the brand identity of those software and hardware solutions that are offered to the end user. For example, Skype, Google Voice, etc. Thus, open technologies are SIP-telephony.

The third interpretation says that both of these species in the process of natural development of the communication market are in fact one and the same group of technologies, namely those that are based on predominantly hardware solutions. And therefore in most contexts can be used as synonyms. In turn, they are opposed primarily to software communication methods - the same voice services Skype and Google.

The fourth interpretation, within the framework of which the distinction between the concepts of SIP and IP-telephony is differentiated, is based on the difference in order to build corresponding communication infrastructures. Typically, SIP-standards allow you to organize typically telephone networks with a wide range of functions related to redirection, the use of an answering machine, etc. IP-telephony allows you to build an infrastructure with a wider range of possibilities. So, not only telephones and automatic telephone exchanges can be connected to the network, but also systems like "smart home" or those devices that are usually classified as "Internet things".

Distinctive features of technology

What is the unconditional distinctive feature, which is characterized by SIP-type Internet telephony? Probably, this is the same openness, the use of free, flexible in the configuration of protocols. In this regard, we give the answers to the question: "SIP-telephony - what is this?":

- VoIP communication with open protocol;

- IP-telephony, based on free technologies;

- a predominantly hardware solution (very similar to a conventional phone);

- A system in which a typical "telephone" type of device operates.

But at the same time, we take into account that each of these interpretations can be correct (as well as having censures from IT experts adhering to other classifications, which we have not indicated, but they are). But the first criterion can be considered as the first criterion - where it is a question of openness of communication technologies.

Why do I need SIP telephony?

Having dealt with the peculiarities of such technology as SIP-telephony (what is it, what are its distinctive features), we can try to answer the question of why it is, in principle, necessary. Than it is better than standard telephone communication (if to speak about hardware implementations of this technology) or Skype, Google Voice (relative to software solutions)? Experts identify the following features of communication through SIP-protocols:

1. Connection rates are generally significantly lower than when using closed commercial applications.

2. More flexible configuration (in most cases) of SIP-systems, when it comes to corporate use. Using modern equipment and software, you can turn a SIP-system into an analog of a full-fledged automatic telephone exchange. At the same time, the cost of implementing appropriate solutions will be incommensurably lower.

3. The ability to receive incoming calls to a landline number. The same Skype is focused mainly on Internet communication of users, each of which has a program loaded, and it works in the "online" mode. They do not have a telephone number in the international format (unless they ordered a "virtual" one). Call the phone working in the SIP-system, you can with a conventional device, and with a cellular. There are two options. Within the first one, the access number provided by the SIP provider and the unique subscriber ID are used. In the second case, a "virtual" direct number is attached to the user account, which looks exactly like a standard phone in an international format.

It is noteworthy that the "virtual" number, or offered by the provider, does not have a real geo-referencing. They may include code specific to a particular country or city, but this does not mean that the subscriber must be in the appropriate coordinates.

Advantages of SIP-telephony

Thus, the main advantages of SIP-telephony for home or office, when compared with a standard ("analog") connection, are:

- cheaper tariffs (and in many cases - equipment);

- lack of "binding" to a specific place (you can communicate wherever there is Internet).

In turn, the advantages of SIP-technologies in comparison with software solutions, such as Skype, are the following:

- cheaper in many cases calls to ordinary phones;

- the ability to receive incoming calls from stationary devices.

Principles of SIP-telephony operation

How does SIP telephony work? Configuring a SIP connection - is it difficult? The principles of both are very simple.

This type of communication works like this. The subscriber registers his account with the provider of SIP-telephony or the provider. He gets a personal number in the SIP-system, as we said above. As a rule, it is five-digit (but there may be more numbers). Once a subscriber connects to his account using a special program or a phone adapted to SIP technology, he can make or receive calls.

As for outgoing calls, everything is simple: you need to act as if in the hands of the user was a regular phone (dial the desired number in an international format). With reception of calls it is hardly more difficult. There are two schemes - with the use of a virtual telephone number and without it. What is the difference? In the first case, we buy a number from the same provider or other vendor specializing in their sale (or, more often, renting it on a monthly basis), and then redirecting it to a SIP number. The structure of the latter looks like this: first comes the access number specified in the international format, which belongs to the provider. For example, this: +7 495 7776675 (popular now Zadarma). Then - "additional" and at the same time a personal number of the subscriber. In the case of Zadarma, he is usually five-digit. Between the main and the second number, the program settings for redirection usually put pause signs - p.

You can call this way through a virtual number - then the call will be automatically redirected to your account. Alternatively, we can use the access number of the provider, plus an additional number, the one that is linked to the subscriber's account. Provided, of course, that a person is online via a program or device that supports SIP calls.

SIP Telephony Features

How can useful SIP telephony options be used in practice? There are a lot of options here. Consider an example where a SIP number can be used on a business trip as an excellent alternative to expensive calls using a conventional phone.

SIP-operators working in Russia, establish close cooperation with foreign ones. Therefore, their subscribers can use all the advantages of the appropriate communication technology while abroad. This is possible, in particular, due to the introduction in international practice of an element such as the SIP server code.

SIP server code

What it is? The fact is that it allows a Russian subscriber who is on the territory of another country to call to his home using the number of a local provider, rather than the one that operates in the Russian Federation.

A simple example. We are, say, in Italy. Suppose, we need to call to Russia to the SIP-number of a friend (provided that at hand - only stationary, for example, hotel, phone). We can make a call in two ways:

1. Dial the friend's number using the Russian access code of the provider. If it's Zadarma, then the figures are: + 7 495 7776675. And then enter the five-digit subscriber number. But this, most likely, will cost us very dearly. Calls from Western Europe to Russia are not cheap.

2. Call a friend using a similar one instead of a Russian access number - but for a local provider. And in combination with the SIP-server code Zadarma. The access number of the local provider can be found out by using the resources of the relevant direction - there you can specify the country and the city where we are located. Suppose we are in Turin. And then the appropriate option would be this: + 39-011-19887800. The SIP server code for Zadarma we will find in the same directory. It is four-digit and quite easy to remember - 9791.

How to call? First, dial the number in Turin. Then we wait a short pause and enter the code of the SAD-server Zadarma. And after - the five-digit account number of our friend.

International call free of charge

A very important point, exciting the person who turned his gaze on technology such as SIP-telephony, is the tariffs for the call. What will they be like? Most likely, the lowest. Since we are calling from a hotel in Turin to a number in the same city, the connection is most likely to be free. Redirection from the Italian access number to the Russian SIP server code, in accordance with intercorporate agreements, is not charged. An incoming call to a friend's number is probably also free (if it does not involve redirection). As a result, we either do not pay for the call at all, or pay a very small bill for a local call to the Turin room, which the hotel can set up for us. We are dealing with a unique phenomenon: we have an international, and with a high probability, free, SIP-telephony.

INUM numbers

Above we said that to call a subscriber without using the access phone of the provider, which may seem not very convenient, it is possible by using the "virtual" number. However, relatively recently, Russian users are also available a third option for making calls. It implies the use of the "global" phone number iNUM. What is its specificity?

The iNUM number is entered into use by the international organization ITU. In principle, it can be considered a kind of virtual number. It always starts with the code +883 (510), and this rule is the same for all subscribers connected to it, regardless of their citizenship and country of actual location. INUM numbers can issue local SIP-telephony operators.

It should be noted that the tariffication of outgoing calls to iNUM from fixed phones is very unattractive. In many cases it is cheaper if a person has a national telephone number. And therefore it is advisable to use the variant with iNUM only if the calling subscriber uses the program for SIP-telephony or SIP-device. Ideal - if both are connected to the same provider. But even if it is not so, it's not critical. Tariffs for such calls from providers are not as high as those of fixed line operators, such as MTS or Rostelecom. SIP-telephony, as we said at the outset, is characterized primarily by lower communication costs, compared to traditional technologies. In some cases, tariffs for calls to iNUM numbers are quite low among VoIP-services - the same Skype, Google and their numerous analogues.

SIP-telephony and hardware solutions

We will study this aspect, such as the use of SIP communication capabilities with the help of hardware methods. What solutions can be used here? Experts call the following three groups:

1. Use of SIP-applications for mobile devices. In this case, the hardware implementation of the technology will be a smartphone or tablet. All that is needed for the conduct of communication sessions is stable access to the Internet. However, the speed need not be high. As a rule, for a qualitative voice connection, a channel of 100-200 Kbps is sufficient. The best stability will be provided by a Wi-Fi connection (provided that it is "distributed" by a router connected to a DSL or fiber optic link), as well as 3G and 4G-standards.

2. Using SIP-devices. Externally, they look exactly the same as the usual analog phones. SIP access is configured (despite the absence of programming interfaces in most cases) easily enough - according to the attached manual, as well as instructions from the provider's website. When choosing the appropriate device it is important to purchase one that is compatible with the technology of Internet access. Most modern phones use Wi-Fi.

3. Using SIP adapters. These devices provide a "middleman" function between conventional, analog, telephones and an Internet channel (most often in the form of the same Wi-Fi connection). Some of their models support simultaneous connection of several telephones.

Of course, you can take advantage of very many SIP-telephony features and with the help of a computer connected to the Internet. The corresponding programs allow you to make and receive calls while communicating with other SIP subscribers or people using a regular phone.

The main condition for the functionality of all three communication formats is the availability of a stable connection to the Internet. The best option is one of the modern wire technologies. You can also use a mobile device in the coverage area of a mobile operator with a good signal level and support for high-speed standards for accessing the Network.

We should also note the universality of such technology as SIP-telephony. That it is not only a communication standard, but also a full-fledged mechanism for organizing communication within a large (and not so) office, at home, an excellent savings tool when traveling abroad, to communicate with friends and business partners in other countries - you will be convinced right away!

Most modern providers offer options not only with receiving and forwarding calls, but also with the purpose of recording voice messages, distributing incoming calls to addresses, using answering machines, using callback functions and other useful features. In this case, the quality of communication in most cases is not inferior to what is achieved on the most modern digital telephone lines.