What is ip pbx. IP PBX Asterisk - principles of operation and use cases. Cloud PBX - reliability and innovation

What is Asterisk IP PBX, how it works, use cases and perspectives

O. Tereshchenko

Today, it is not profitable to buy a conventional or digital PBX for a small office or Call-center. Traditional telephony has been replaced by IP telephony, which is characterized by low call cost, ease of deployment, ease of configuration, scalability and connection security.

IP PBX - a telephone exchange that provides voice transmission over the Internet (based on the Voice over IP protocol).

In this article we will talk about IP-telephony, organized on the basis of program IPATS "Asterisk».

IP PBX Asterisk today is the best solution for organizing office telephony and an inexpensive call center. This is a software product of the Open Source class - free software with open source. Due to the unique combination of many functions, Asterisk takes the leading position among platforms for creating office telephony. The price also plays an important role. The cost of office IP-telephony on the Asterisk platform is several times lower than the cost of solutions on traditional IP PBXs - Panasonic, Samsung, etc.

Hardware

Asterisk supports any Voice over IP (VoIP) hardware. Devices from various manufacturers of VoIP equipment can be connected without any problems.

Functionality

Asterisk has all the features of a classic PBX, supports many VoIP protocols and provides voice mail, conferencing, interactive voice menu (IVR), call center (queuing calls and distributing them to agents using various algorithms), CDR recording and other functions. Asterisk has no restrictions on the number of subscribers, channels and functionality.

To create your own functionality, you can use the Asterisk language to write a dialplan. To date, many graphical web shells for Asterisk have already been written for ease of use and ease of perception.

Implementation

1. Let's start with the fact that Asterisk is installed on Linux.

The first question is which implementation option to choose. Actually, the main choice is the "flat" Asterisk, controlled through the command interface (using the command line),

or the Asterisk system with a Web interface (as already mentioned, a sufficient number of them have been written).

The first option provides more flexibility and more features, and the second one is easier to set up and manage.

For office tasks and small business tasks, the implementation of complex logic is not important. Therefore, here we focus on building a simpler system designed to serve up to 100 internal telephones with multichannel input lines from one or more telephone operators.

2. The second practical question, to be decided - which platform to choose to use Asterisk. Two options: local server or "cloud"?

A local server for an IP-PBX in modern conditions can be almost free: let's say there are old (or not very old) computers. All you need: 2 GB of RAM and one processor (you can even use some old and not very powerful one).

But - Attention: if the old computer is really junk ... Then such a server can let you down, refusing at the most inopportune moment. And then the effect of saving the company money can be quite the opposite.

To date, the cost of a computer system unit for deploying an IP-PBX in an office does not exceed $200.

So, the issue with the server is either resolved, or we are heading “to the clouds”.

Virtual PBX

An obvious plus of the cloud is that the cloud provider is responsible for the reliability of the work and there is no need to spend money on a server. The monthly fee for a virtual "server" of one core and 2 GB of RAM will not be high: about 1000 rubles (or even less). You can also use a cloud PBX (the operation of a virtual server and a cloud PBX has a slight difference).

A little about the "pitfalls" of a virtual PBX

Telephony operators offer different conditions for using their cloud PBXs. There are restrictions. These may be restrictions on the number of internal numbers, all kinds of functional features. For example, not all such systems provide the ability to record conversations, not all types of IP phones are serviced, and sometimes the quality of communication suffers.

There is a set of restrictions common to virtual PBXs of all telephone operators. It consists in the following: virtual PBXs do not allow simultaneous connection of other telephone operators or switching to another operator. Therefore, you will not be able to optimize costs by automatically choosing tariffs for specific connections, or use another operator with the current virtual PBX.

Those. the telephone operator, using its virtual PBX, can primary stage to provide a solution to telephony issues. But at the same time, a serious barrier will be placed on the way of further development of your company's communications.

Another point to consider is the situation in which one extension needs to call another extension. In this case, the conversation of subscribers will take place in a “big circle”, that is, from the set of internal Subscriber 1, the signal will pass to the office router with access to the external network (on which the corresponding ports must be opened, which in turn increases the “attack area”, since you need to open SIP ports for each device), come to the virtual IP-PBX server (cloud PBX) located in a certain data center, after which it will return to the original router and from the external line will be sent to the internal one to the device of the internal Subscriber 2. Long way isn't it? And if there are more than a dozen such connections?

Security can become a problem because one internal user will go outside while talking to another internal user. Such a structure is often hacked and "pumped" calls through it, say, from Nigeria to Palestine - to expensive paid numbers, and through all available channels. Overnight, your company can lose a huge amount, and it's good if the telephone provider has introduced restrictions for such cases, then the losses will not be so significant. In general, any SIP port visible on the Internet (which I mentioned above needs to be opened) is attacked within a few minutes after it appears, so protection issues must be worked out carefully and professionally, since the more ports are open, the larger the “attack area”.

In this case, the “traffic” passing between internal subscribers must be encrypted, since in this option all conversations between internal subscribers will not be difficult to listen to (intercept).

IP-ATScusing the server

In the case of using "your" server (located within the network), the picture will be different.

Your server:

Minimizes the "attack area" (because it reduces the number of open ports);

Allows you to exclude the very possibility of listening to (intercepting) the conversations of internal subscribers or connecting to a third-party subscriber on behalf of an internal one, even if there are remote offices (since internal subscribers talk to each other without going to the "external network");

1. IP-PBX: what is it?

In recent years, almost all leading manufacturers of switching equipment have released PBXs ( PBX, Private branch exchange or Private business exchange - PBX or PBX) with the ability to transmit voice over data channels, including via the Internet using the SIP protocol ( Session Initiation Protocol - session establishment protocol). They began to be called IP PBX (IP-PBX).

SIP(eng. Session Initiation Protocol - session establishment protocol) is a technology that allows you to make a telephone conversation over the Internet or a local area network of an enterprise. When using this technology, a direct point-to-point connection is established between subscribers. Thanks to SIP technology, you can make video calls.

Ordinary office PBXs use circuit switching technology: when receiving a call over a copper line, the PBX switches it to internal numbers in the office. IP PBX uses packet switching technology, i.e. the call to the PBX arrives via a data network channel and is then redirected to a special phone that supports a SIP connection. As a SIP phone, you can use not only a stationary device, but also a soft phone (SoftPhone) installed on a computer or mobile phone. The latest models of smartphones with the Android operating system already have built-in support for receiving and making calls via the SIP protocol.

2. Scope of IP-PBX

The emergence of IP-PBX is associated with the rapid development of computer technology and the emergence of corporate data networks and, as a result, the demand for equipment that allows you to use the same communication channels for the transmission of voice traffic, data, fax messages and video information. Modern IP-PBXs convert speech into standard IP packets and send them over a communication channel, where they are transmitted along with data packets.

IP packets- these are blocks of information transmitted via the Internet or the local network of the enterprise.

Thanks to the use of Internet channels for the transmission of voice traffic, connecting an office PBX has become just a matter of setting up authentication data on the side of the telecom operator and the subscriber who has an IP PBX installed. The departure from traditional wires also allowed subscribers to painlessly change rented premises. when moving from office to office, the existing numbers of the organization are retained, and to connect the PBX, only the presence of an Internet channel is required.

In the case of using IP-PBX in a company to organize telephone communication between several offices, it is possible to significantly reduce the cost of using the channels of fixed-line operators. Connecting several PBXs over IP channels is usually cheaper than using other protocols (ISDN BRI, PRI, E&M, and others). Also, thanks to the use of IP technologies, subscribers of a modern PBX can be outside the office, connecting to a PBX from anywhere from any device that supports voice transmission using the SIP protocol.

3. Advantages of IP-PBX (IP-PBX)

Virtually unlimited number of lines and subscribers- unlike conventional PBXs and mini-PBXs, which have the maximum capacity of external lines or internal ports, IP-PBX can be expanded almost unlimitedly, and both external lines and internal subscribers can be connected in various ways;
IP-PBX allows unite divisions and branches of the company into a single telephone network located in different places (another city or country), while all subscribers, regardless of their location, will be subscribers of the same PBX, which will make all calls between branches free of charge;
With IP PBX, you can organize an interactive voice menu (IVR) or the so-called "intelligent secretary", with the help of which you can process incoming calls automatically;
IP PBX provides all the functions of modern PBXs- call forwarding (according to various customizable rules), call hold, call interception, group call, etc.
Various call forwarding options both between internal subscribers and on mobile phones of employees who are out of the office;
Centralized call recording on the IP-PBX server allows you to save information about all calls made;
conferencing- conferences with the connection of both internal and external subscribers;
Ability to install restrictions on making long distance or international calls for different groups of subscribers;
The system is easy integrates with CRM systems, databases, etc.;
On the basis of IP-PBX it is possible to organize call center(call center or contact center);
IP-PBX allows you to organize the system automatic fax reception and forwarding to e-mail Possibility to organize a voice mail system;
Manager IP-PBX interface is accessible through a web browser, which provides ease of control and change of the desired parameters;
Based on IP-PBX, it is possible to implement video telephony systems, which will allow employees to communicate not only by voice, but also provide visual contact.

In addition, based on IP-PBX, you can organize unified communications system(unified communications), which will allow your company's employees to always be in touch.

4. How to choose an IP-PBX? Criterias of choice

The IP-PBX implements the packet switching function, which means that such an PBX is a small computer with its own operating system, processor and memory. As a rule, a special version of the Linux operating system with a proprietary software package that provides call control and additional services is installed in an IP-PBX. As a rule, Asterisk software PBX is used.

Asterisk is a full-fledged software PBX. It can run on operating systems such as Linux, BSD, Windows and OS X and gives you all the features that a regular PBX has and more. Asterisk is based on protocols that enable voice transmission over IP-based networks (Internet Protocol) and, due to this, this PBX can work with almost any IP-telephony equipment that uses standard protocols for VOIP, while using a relatively inexpensive Hardware.

Thus, the main thing you need to pay attention to when choosing an IP-PBX is its performance. The performance of stations based on packet switching technology is determined by the number of simultaneous connections. It depends on how many people can talk on the phone at the same time.

You also need to pay attention to the size of the memory installed in the IP-PBX. The amount of memory will determine the number of minutes of voicemail and recorded conversations saved. In case of its shortage, old records of conversations and voice mail will be deleted.

A Virtual PBX can be used to create and upgrade a corporate communications network. With its help, it is easy to build and optimize all communication processes for business.

On the basis of a Virtual or mini-PBX, you can combine all communication channels into one: from regular calls and notifications about customer and partner requests in instant messengers to creating automatic tasks in an integrated CRM or ERP system.

Benefits provided by IP telephony for the office:

line availability for receiving and making calls;

the possibility of free connection of an unlimited number of internal numbers for employees;

the ability to use for connecting subscribers a connection both via a conventional telephone network and based on an IP network;

high quality and stability of communication without disconnections, noise, interference and other defects that may interfere with comfortable communication;

advanced functionality of a virtual IP-PBX, especially when using the integration of virtual telephony with customer relationship management systems (CRM and ERP), not to mention traditional tasks (receiving and transmitting a fax, saving conversations and call forwarding);

lack of binding to the location of the office;

the ability to connect dynamic call tracking to track the effectiveness of advertising.

* - uninterrupted operation of communication is guaranteed when routing calls only through our company's networks (without transitions to / from the partner network) and in case of force majeure.

Cloud PBX - reliability and innovation

Cloud telephony is a modern platform for companies with any staff, including those with remote employees (working outside the office). Enjoys great success with businesses in Moscow and other cities of Russia.

Virtual PBX is a full-featured telephony service, the technical base of which is based on the duplication of all infrastructure elements, which guarantees uninterrupted operation and data storage, including call records. The optimal cost, the ability to integrate with other business tools and the expansion of functionality make it possible to use an innovative product every day.

You can use a cloud PBX in the office without telephones at all - a computer or laptop connected to the Internet is enough: all resources are actually located at the provider. The number will also be virtual, that is, without reference to the office. You can connect and configure the Virtual PBX completely remotely.

Connection in 3 hours

The selected number will become available for receiving calls immediately after the conclusion of the contract

No link to address

No wires, no hassle with moving or opening new points of presence

Favorable rates

Connection of a number from 0 rubles, fee for the number from 250 rubles / month, a minute of conversation from 0.42 rubles.

High reliability

UIS communication infrastructure guarantees stable operation - no more than 15 minutes of downtime per month *

Easy Connectivity

It is easy to connect and disconnect functionality and pay only for the tools and features used

Technical support 24/7

And a personal manager for convenient work with telephony, Virtual PBX and other tools

Opportunities of virtual PBX for business

Online shopping

Automation of order processing

Call centers

Agent Control and Call Distribution

Service companies

Tracking all stages of interaction with customers

Financial institutions

This is a great solution for companies that value mobility. IP-telephony can work from anywhere in the world and does not require changing the phone number. Cloud telephony allows you to make any settings up to the scenario of choosing a specific operator when the specified conditions in the Personal Account are met, which makes the Virtual PBX a very flexible tool that adapts to any needs and tasks.

Connecting smart telephony from UIS allows you to use various tools: a call from a site (sitephone), a lead generator and an online consultant. With their help, the company can provide customers with additional communication channels. Connecting a Virtual PBX is an important step for business growth.

First of all, it is distinguished by its focus on a small number of serviced numbers (usually no more than one hundred or two hundred), the division of the telephone network into “internal” and “external”. Depending on the type, it can receive a digital stream from telephone operators, analog lines or via switched networks (IP-telephony). Subscriber devices are usually analog phones, digital or IP phones. The use of PBX allows you to refuse to connect each subscriber device (telephone, modem, fax) of the organization to the public telephone network, which would lead to the allocation of a separate line to each subscriber device (usually paid monthly), and all "internal" calls would go through the PBX telecom operator.

PBX equipment is usually installed at the premises of an organization and switches calls between internal subscriber lines. Additionally, a limited number of trunk lines (trunks) to the public switched telephone network are typically available for external incoming and outgoing calls. Multi-building organizations can use trunks (CO, from the Central Office) to connect their own PBXs. Trunks are typically analog or may be digital (E1, BRI). The latter, unlike analog ones, are able to process more than one connection and receive calls to several city numbers - DID.

Sometimes the English abbreviation is used to refer to the PBX PBX(short for P private B ranch e X change - or P private B business e X change) and also PABX(from P private A automatic B ranch e X change).

The main difference between a production PBX and a city telephone exchange ( GTS) are:

the ability to provide fully accessible traffic switching schemes (communication without blocking);
intelligent call distribution systems for subscribers or operators;
the huge volume of subscriber services provided (for example, Avaya PBXs provide over 800 telephone services);
support for built-in CRM subsystems and advanced SDK systems for embedding telephone subscriber service in automated systems;
ensuring the provision of subscriber service packages, regardless of the location of the subscriber and the method of his connection to the telephone network (mobility);
high reliability and flexible redundancy system providing 100% continuity of telephone communication.

PBX allows you to save money for the organization and reduce communication costs, since when using PBX, internal calls within the organization are free, the connection establishment time is extremely short, since three-digit numbering is usually used, and each organization can program its PBX to suit its needs, distributing it among employees the right to enter the city, the city lines available to the organization, setting up voice menus, and so on.

On the basis of the PBX, large corporate telephone networks are being built for government and financial institutions, transport management systems, medical institutions, etc. Office PBX programming is carried out using a system phone, or using a special program connected via the port (interface): RS-232 ; USB; 10BASE-T. You can usually set a password to enter the programming mode so that unauthorized persons cannot change the set operation algorithm of the mini-PBX (PBX). Such a system telephone should be installed at the secretary or at the secretary and the director, however, if there are enough expansion cards in the PBX that support system telephones, such devices can be installed by everyone.

The capabilities of the PBX are determined by its configuration. For example, you can equip the station to the maximum with analog subscriber cards in order to achieve maximum capacity, or you can give priority to city line cards. In addition to these types of cards, there are many other cards, such as auto attendant card, voice mail card, modem card, music source connection card, and so on. Different manufacturers of PBXs can have very different station configurations.

Main functions

Switching of subscribers within the office telephone network.
The ability for subscribers to make calls to the city (usually with the addition of “9” before the city number), that is, the organization of interfacing with the public switched telephone network (PSTN).
Receiving city calls and directing them to specified internal numbers (see also DISA)

Types of office and office automatic telephone exchanges

Traditionally, telephone exchanges are divided according to the type of switching and the number of connected telephone lines (capacity).

According to the type of switching, analog, hybrid and digital exchanges are distinguished. Currently, various manufacturers produce stations of all three types. Analog stations have the lowest port cost. Hybrid PBXs differ from digital ones in the way the signal is switched. In digital exchanges, the voice tone signal is converted into an encoded digital electrical signal (having only two logical values: "0" and "1"). These signals are then switched. In hybrid PBXs, “not digitized”, that is, an analog electrical voice signal without conversion, is switched. At the same time, the control programs of hybrid PBXs are similar to those used in digital PBXs. The user interface may be the same, and in some cases the station subscriber will not even feel the difference between a hybrid and a digital exchange. The term "hybrid lines" means that both proprietary and analog telephones can be connected to such lines.

With the spread of the IP telephony standard, IP PBXs have become widespread.

Manufacturers

Additional features

Reservation of telephone communication from several operators (if communication with one operator is lost, the lines of another are used).
Call forwarding on a busy signal, on no answer, or unconditional, depending on the time of day and other conditions, that is, composing call processing scripts or dialplans (dialplan).
Transferring a received call to another subscriber.
Picking up the handset for another subscriber (call interception).
priority calls.
Extension Dialing for Incoming Connections (DISA).
Group call, call center organization
Serial search - selection of a free trunk for outgoing connections.
Automatic change of guidance table depending on the time, day of the week.
Notification of the subscriber about the off-hook (loud signal into the handset some time after the end).
Speakerphone, reception and broadcast of civil defense and emergency signals.
Control

Computerization has affected traditional telephone communications, and the interface of traditional PBXs with access to the city, intercity and international telephone network with a personal computer significantly changes the face of modern telephony. However, as before, in most modern offices, separate wiring is used for telephone and computer networks, which is not always convenient and, moreover, makes it difficult to access telephone communications when working with various applications. Therefore, various systems have appeared that allow the joint operation of telephone and computer networks on the same wiring - telephone or computer.

LAN-telephony is understood as such an organization of telephone communication, in which in a building with a local area network, there remains (in addition to power) only one signal wiring - either computer network (for example, Ethernet) or telephone. In this case, both computers and telephones are connected to the same sockets.

To organize telephone communication in these conditions, alternative PBXs are used (also called pseudo-PBXs or un-PBXs) - these are PBXs based on personal computers (PCs). Those non-PBXs that use the same signal wiring for telephony and data transmission can be categorized as LAN telephony PBXs.

Systems of this class are usually divided into the following three main categories:

Distributed LAN-PBXs. These systems consist of several elements: telephone servers, gateways and telephone switches.
Integrated communication systems (all-in-one-box) are specialized devices with embedded OS and application software.
IP Gateway PBXs are traditional PBXs that have IP Gateway cards installed for IP communication.

Companies have followed different paths to LAN-telephony. Those that were engaged in the supply of equipment for computer networks offered the so-called distributed solutions that do not provide for the presence of a PBX in the office in the usual sense (Cisco, etc.). Companies specializing in the production of traditional PBXs began to equip them with IP gateways - boards inserted into those PBXs that are already being produced and are in operation (solutions by Avaya, Ericsson, Siemens, Alcatel, Samsung, etc.). These same companies began offering integrated communications systems.
All of these systems are based on a common signal wiring and have centralized intelligence concentrated in the core of the system - the server or PBX processor.

Distributed Systems

In LAN-telephony systems with distributed switching, the switching process is carried out in a local network. All such systems contain switches, IP phones, gateways, in which voice packets do not necessarily go through the central core; packets receive authorization and routing from the intelligent core and are routed to the phone or gateway. In such systems, the principle of distributed switching is implemented - it is carried out not on the switching field, but in the network itself. At the same time, call service servers are connected to the LAN and are used to establish and disconnect traditional telephone connections, as well as to perform additional functions, such as voice mail. As a rule, after a connection is established in such systems, the servers are turned off, and the subscribers' phones exchange voice packets directly.

In Russia, there are currently similar systems with Ethernet-IP and ATM technologies.

The vast majority of LANs around the world implement some form of Ethernet technology (a typical network structure with a distributed LAN-PBX based on Ethernet technology is shown in Figure 1). However, if you urgently need to deploy a telephone and computer network in a building where there is only telephone wiring, it is advisable to stop at distributed solutions for ATM LANs. In this case, high quality telephone communication is provided, but network performance is significantly lower than when using Ethernet. In this case, telephones (analogue or digital, depending on which telephone network is actually installed in the building) are connected to the network directly, and computer network equipment is connected via ATM modems. However, most often enterprise-class ATM is implemented on twisted-pair wiring of a fairly high category, and the choice of this technology is dictated by the structure of data, voice and video traffic.

Network with integrated communication system

An integrated communication system (sometimes called an integrated LAN-PBX) combines the functions of the following devices: LAN switch, IP router, remote access server, VoIP gateway, and PBX. In integrated communication systems (IP-PBX), switching is built mainly on the basis of PBX. In this case, the PBX is usually supplemented by a LAN switch and an IP router, which is why it is called an integrated communication system. Connection switching is carried out by the telecommunications server in accordance with the list of services available to a particular user.

The main advantage of such systems compared to distributed ones is greater functionality, and with systems based on the modernization of existing PBX by installing additional VoIP gateways - also greater transparency.

Products in this category in Russia are represented by 3Com, Alcatel, Avaya, Samsung and Nortel Networks. Smaller companies such as Merlot Communications, Network Alchemy, Praxon and Vertical Networks also sell overseas. The block diagram of a network with an integrated communication system is shown in fig. 2.

When starting to choose hardware and software solutions for organizing LAN telephony in your office, it makes sense to be guided by the following considerations.

If your office has already deployed Ethernet and a telephone network, then you probably have a PBX installed from a reputable manufacturer. In this case, it is advisable to stop at an intermediate solution - purchase an IP gateway and install it in the PBX.
If you're busy setting up a new building and installing new wiring, an advanced distributed solution or an integrated communications system is the way to go. However, in terms of one workplace, this will apparently be more expensive than a PBX with an IP gateway.
An integrated communication system is preferable to a distributed network solution if users are accustomed to receiving a variety of telephony services provided by traditional PBXs (call transfer, follow me, parking, pick-up, announcement, etc. - about 200 functions in total). Distributed LAN-PBXs support only basic PBX functions (usually 10-20, in any case, no more than 25 basic functions), but in some cases this is not enough (for example, in distributed systems, as a rule, there is no barge in - operator intrusion into a conversation ). In addition, problems may arise when connecting to a city PBX using signaling methods specific to Russia.
If you have already settled on the most suitable solution, then when choosing a vendor, you should consider factors such as ease of configuration, the ability to receive updated software, scalability, variety and completeness of functions. If the main thing is reliability and fault tolerance, then pay special attention to the possibility of equipment clustering provided by Cisco Systems. Some vendors also use core component redundancy (eg Alcatel OmniPCX 4400).
If your company has a corporate ATM network installed, then the options for choosing a PBX are drastically reduced. Before choosing a specific supplier, it is advisable to analyze the above factors.
Even when a decision is made to deploy equipment of a particular company, it will not be superfluous to use LAN telephones from different manufacturers. The vast majority of such devices are considered compatible, but this only applies to IP devices. In fact, such compatibility should be tested in practice. 3Com's equipment is almost incompatible with phones from other manufacturers.
When choosing hardware and software, one should take into account such factors as the cost per line or port, including the cost of a telephone set. The analysis showed that according to this indicator, the proposed solutions differ significantly - from $110 (Samsung) to $1000 (Nortel Networks and Cisco Systems). The specific value of the cost strongly depends on the configuration and delivery conditions, which are determined by the contract.
The expediency of the transition to the active use of IP-telephony in corporate networks does not raise any particular doubts. However, when purchasing and deploying a corporate IP telephony system, you should first of all think about what you need it for. The fact is that by leaving one wiring instead of two, you can get a system with less reliability, although more functionality. Therefore, weigh in advance all the possible consequences of such a responsible step.

Standards and Algorithms

When creating LAN telephony systems, two basic standards are used - H.323 and SIP. To date, the most widely used standard is H.323 ITU, which was developed with the task of “adapting” telephone equipment to work in computer networks. This standard is close to traditional signaling systems (circuit-switched based on the Q.931 protocol), so it is most widely used in systems developed by traditional telephone equipment vendors. It became the first standard protocol for IP telephony.

The SIP standard was developed by the IETF problem group and implements a simpler, Internet-based approach to HTTP-based signaling. Therefore, it was precisely those companies that traditionally produced equipment for computer networks that began to use it. However, everyone predicts a great future for this standard in LAN telephony, as it reflects the main trend - the “internetization” of telecommunications. To date, the SIP protocol is rapidly spreading, including thanks to the efforts of SIPNET. Some features, such as conferencing, are better supported by SIP than by H.323. Therefore, for the time being, you should choose a solution that supports both of these protocols, and in the future, you may want to switch to using the SIP protocol. Some companies also use their own proprietary protocols (for example, Cisco Systems' Skinny Gateway Protocol, which was open by them for use by other companies).

Telephone sets

Currently, the workplace of a company employee can be equipped with voice communication in one of the following ways:

Phone for direct connection to a LAN socket. In the case where Ethernet technology is implemented in the LAN, this is a digital Ethernet telephone.
A multimedia personal computer (with microphone and headphones or speaker) equipped with telephony functions and connected to a LAN. The disadvantage of such a terminal device is typical for any personal computer - for example, it can “freeze” and the connection will be interrupted.
Ordinary analog telephone connected to the LAN.
LAN phones are often referred to as IP phones. They should not be confused with system phones - digital telephones manufactured by the same company as the rest of the telephone equipment, or a terminal.