In this article we will talk about IP PBX software(Especially about the Asterisk family) - the foundation of modern corporate VoIP telephony. We will look at their main possibilities, cunning adjustments, and, most importantly, we will objectively analyze the pros and cons of these solutions. Let’s also try to estimate how many companies would actually benefit from a “no-crash” (on-the-fly) IP PBX software.

The PBX office was and will be deprived of one of the most important tools for the combination of competitive business organizations with “statistically average” citizens (potential suppliers of goods and services), partner companies ners, suppliers of materials and components, distributors and representatives of ownership structures. The basis of its functionality is initially the task of connecting the subscriber's telephones, which calls and calls, supporting the call session and releasing the connection after completion of the call. Before these “three pillars” of voice line commutation, more and more new functions and services were gradually added, and now they reach two to three dozen (depending on the PBX model ).

All good daily mini-PBXs, pros for companies that are just starting their business, the price created on their basis for internal telephone communication sometimes seems “incredible”. And in search of a cheap (or equivalent in functionality) technical solution, startups are going to the computer segment, or VoIP telephony, which makes it possible to transmit voice and digital information in one channel (and a local computer the company already has measures for “determination” ).

In this segment of the left part of the market, installation telephone exchanges are required, the work of which is based on the IP protocol (Internet Protocol), designed to organize the exchange of data in digital form (including language) using additional packet switching (we guess that is traditional This phone uses circuit switching ). Such stations create a class of IP-PBX, with two groups that are included before: 1) hardware IP PBX and 2) IP PBX software, mainly Linux distributions or compiling files under Windows OS. Talk about another group in today's report.

The software IP PBX has all the functions of analogue, digital and hybrid telephone exchanges that are connected to switches, routers and other hardware devices, compatible with a special software that is installed on any server or desktop that is used in the company ii

Another group of IP-PBX class was equipped today with about 20 versions of the so-called “free software” with a closed code, which gives its associates the right to add new functions, such as Windows demand At this rate, half of the area of ​​free software security for software automatic telephone exchanges will be reduced to cost-free products. And among them, the crazy leader is IP-PBX Asterisk, which was far ahead of its competitors, sharing approximately 15% of the IP-PBX market with closed code among itself. And the majority of “starting” small business companies rely on it.

Advantages of software IP PBXs

Why do you think there is such a high level of popularity of IP-PBX type Asterisk (Asterisk in English translation is a star)?

First of all, it has a new set of basic and additional PBX functions in its arsenal.

In another way, it works with Skype.

Thirdly, it will provide video calls.

Fourthly, its capabilities can be expanded, for example, in part of the parallel service of dozens and hundreds of telephone connections, so that to the server with installed Asterisk software, connect computer boards to ensure connections high-capacity lines type T1/ E1.

Competing cost-free programs, designed mainly for IP-PBX specific applications, do not have such a set of characteristics (although in their areas, they can outperform Asterisk in other areas).

The administration of Asterisk can operate in a number of graphical ways, but you can choose most clients, as a rule, on the FreePBX web interface, which can be used without much difficulty or replacement There are no subscriber numbers and functions.

Both software phones (softphones) and all types of hardware IP PBX phones (with IP, USB, Wi-Fi interfaces) can be connected to the Asterisk software IP PBX.

The range of functional capabilities and services of Asterisk is gradually expanding without the help of “great sellers”, but such a “plus” can perhaps be appreciated only by the backers, while the majority of those who live I feel more and more difficulties in mastering new versions and ensuring their stable operation. And this, as the extensive practice of using Asterisk shows, is not “terrible” from its short software (as, for that matter, other software PBXs).

Disadvantages of software IP PBXs

Also, the Asterisk software or any other similar IP PBX software can be downloaded on the Internet without any problems. That’s where, unfortunately, the “freedom” will end.

The first article is the installation of Aterisk on the server. The fragments of this complex software, which is used as a platform for the Linux operating system, is an essential tool that is well known on it. So, to install Asterisk you will have to hire an integrator company.

Pleasure from practice is the greatest benefit that you can build a company’s server, which will get you a full-time system administrator before installing and adjusting Asterisk. The ease of putting into operation the IP PBX, which is being built, even in very wealthy companies has led to very large unplanned expenses, including for the elimination of legacy problems (at a lower price).

Another article includes administration and maintenance. To implement these functions, you need a professional working with Linux who knows Asterisk, as well as IP telephony technologies and skills. Such a “dear professional” will have to be accepted into the company’s staff or be “virtuous” at their lava, spending money on his training, and then paying him a high salary.

It’s good to know that the system administrator, who every company gets before administering a PBX, gets up to speed with the basic setup of the system. Advanced routing algorithms or advanced adjustments require dozens of years of digging into documentation and spending an hour on thematic forums. Moreover, parts of the system update (work that is necessary) in the first river or two will lead to you up to one day of new expenses in the office. And everything will continue until your system administrator gets the hang of it.

Thus, the investment and operational support of a cost-free software PBX can quickly outweigh the costs of adding a hardware IP-PBX with an outsourced support service.

The main concern facing companies that use Asterisk is the possibility of external intrusion into the PBX, which can easily be accomplished. The biggest cause of Asterisk malfunctions is the failure to properly configure the basic security settings of the IP PBX software. Another weakness of the protection is due to the fact that, as was generally understood, in Asterisk, “great programmers” often introduce new functional modules (which, of course, can be done by the developers themselves), which add to the basic software security new spills. It is not important for advanced hackers to know the breaches, and as a result of a successful attack, a wave of transit calls will flow through Asterisk, for which you will have to pay a tidy sum.

Telecom and business operators were the first to appreciate all the advantages of IP telephony as compared to analogue ones: the creation of a corporate telephone network based on Internet data transmission channels is already obvious.

The benefits of savings and the ability to expand your corporate IP telephony network have been available for a long time. So, what are the advantages of IP telephony?

First of all, the system is scalable

The advantage of IP telephony lies in the fact that it allows you to quickly change the virtual PBX database: enable or disable subscribers from it. Most functional capabilities are realized through “dark” technologies.
A virtual PBX allows you to have an office structure regardless of the size of your business. In this case, digital communication systems allow the use of virtual channels for data exchange within a single network of branches, which eliminates the need to install equipment in all offices and branches.

In other words, IP telephony is important

The advantage of Internet telephony, compared to traditional ones, lies in the fact that it allows you to save money. As a rule, when switching to IP telephony, the cost of calls will quickly decrease within the first month. In addition, the range of tariffs in this category is wide: the choice of tariffs for IP and traditional telephony cannot be compared.

Thirdly, IP telephony removes the interconnection between stations

Working in the office, behind a flexible schedule or at a remote location, workers are constantly losing contact. There is no longer a need to spend money on calls from departments and calls to branches: all company numbers are connected to the back office.
Digital calling makes it possible to hold conferences or video presentations, automatically forward calls to the required subscribers and carry out other activities that are convenient for wireless communications.

Fourth, ease of data management

IP and traditional telephony are undermined by the fact that they first allow you to deny access to any statistical data and set a framework for making payments. You can establish interconnections or external connections with these or other subscribers.

Most IP hardware phones use SIP protocols, and some of them work independently of the PC.

The advantages of SIP telephony make it easy to connect, and there is no need to install additional lines. In addition, the low cost of SIP telephony is ensured by the characteristics of the channel.

There are actually a lot of advantages to IP telephony, but switching to it needs to be considered, and the possibility of its stagnation can be considered individually. The advantages of digital telephony are not identical, but the shortcomings of IP telephony are the same. The most important of them can be called direct storage on the Internet. The Internet freezes and the telephone connection disappears. To solve this problem, you can use additional redirection: since it is impossible to contact your phone number through your office phone, you can’t call your mobile number.

Another disadvantage: with an individually configured configuration, it is necessary to program the PBX, as a result of which malfunctions are possible, including important things. In most cases, stench can cause harm to patients with diabetes, and in worst cases, they can lead to additional costs for additional problems.

There is also the possibility of evil and theft of data, fragments for communication are compromised by computer monitoring.

I would like to say a few words about the high cost of ownership, as well as about the fact that IP telephony is not the end of the cheapest solutions.

The disadvantages of IP telephony are insignificant compared to its advantages, but the advantages of IP telephony are even more significant.

In order to make the right and final decision, you need to contact the specialists of our company so that you can quickly select the best option for your capabilities and needs.
We are ready to contact our clients after completing the work and are always ready to help and advise if necessary.

Whether advertising is intended to show the best and most advantageous aspects of a product, it will also want to deprive some of its shortcomings. It is often the case that, having identified some disadvantages, people share them one by one, thus emphasizing respect only for them. As a result, interest in the service decreases, and the company wonders why. Has not lost sight of this trend ip telephony. We encourage you to become familiar with various myths about this technology.

Myths about IP telephony

Myth number one: low intensity of sound. IP communications require the operator to improve technical capabilities to ensure Internet speed and clear reception and transmission capabilities. There, where we can not conform, it suffers from the brilliance of the sound. Be aware that such providers offer their services at a reduced price. Also note that in specialized IP phones the volume of sound transmission will be greater than in standard or headset devices.

Another myth: the greatest virtuousness of service. Suchasna ip telephony tariffs In order to be part of the package of services, it offers its employees budgetary options and expansions. For those clients who have received clear service, the operator offers more winning options, if they are more likely to be lower than standard offers.

Myth three: it is impossible for small companies to use this service quickly. Calling on the phone is an invisible part of the work process, and here it is worth mentioning that IP calling tariffs are cheaper and less expensive. As a rule, operators offer a convenient package of services for companies, which often involve interconnections. Creating a single telephone space with one number allows you to secure communications from any client at any time and create a database for a variety of work tasks.

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Problems with NAT

Signaling protocols SIP and H.323 operate by exchanging messages with the IP telephony server. The operator who operates the call and the operator who receives it can be located in different areas behind NAT devices. Regardless of this, VoIP traffic can reach the server, and users will feel the ringing after the call parameters are changed. As soon as the user who receives the call, the media protocol - RTP - enters on the right, which will send packets to the internal address of the remote phone (the internal address itself will be indicated in the forward SIP / H.323 headers ), instead of guiding them to the correct address to NAT. If RTP packets are sent to the correct NAT IP address, most border screens, especially those without cable connection, will drop such packets. So if you decide to use IP-telephony and you have remote networks or branches, be prepared to understand the theory of NAT and configure the Firewall correctly.

Problems with the connection

Circuit switching (TSS) networks ensure that the audio information that is transmitted is unique and does not interfere with the transmission of other services. IP telephony, as a rule, flows with other commercial traffic, such as mail and the Internet. In order to achieve the same high-quality voice quality with local IP telephony, it is often necessary to correctly adjust the traffic prioritization or update the existing infrastructure.

The appointment of the telephone operator

Due to channel switching, information about the subscriber's location is recorded only once when the service is immediately provided to the subscriber and is changed only when the subscriber moves, when Whose number is saved behind him. In combination with the measurements of the dry steel connection, information about the location of the subscriber can be determined using an additional method of triangulation using the obvious coordinates of base stations (mobile towers) or using additional GPS coordinates, such as connects the subscriber's mobile phone. VoIP systems do not have a simple way to identify who is calling, which is often used by all sorts of scammers, bullies, trolls and other dubious individuals. Can you think about the good and the good of giving someone the opportunity to find out about your religious practice? Just think about the safety of yourself and your companions. When you call the emergency number in an emergency situation, the smell also cannot be identified as the one who is calling, but it can ruin someone’s life.

CallerID admin and access to private data

CallerID (CID) – this is information about the subscriber number. It is important for organizations to obtain this information in order to determine whether they can receive a call from a particular number or another. In connection with the telephone network of the foreign exchange, this information is provided by the subscriber's home network. For VoIP measures, the CID is configured by the administrator of the VoIP server. The administrator can be either an honest VoIP telephone provider or a criminal who wants to pretend to be someone else by changing his number (CID).

In addition, some information about the number (CID) is transferred during the process of changing the parameters of a new SIP or H.323 connection, and you can use special programs such as Ethereal, tcpdump and Wireshark. This means that your provider receives your CID, which can still be identified by analyzing the traffic flow of the connection.

Phone interface

IP phones often have a very small interface, which limits the ability to specify a password using only digital values, instead of a reliable password based on the entire ASCII character set. In addition, many organizations do not want to securely remove the password associated with the internal telephone number. (Ext: 3054, Secret: 3054). It is not important to guess that the attacker, who has denied access to the phone, will first try to guess the password and enter the internal number connected to the phone.

SIP authentication attack

During the authentication process to the SIP protocol, passwords are transmitted as clear text, and as a hash sum of these passwords, using the MD5 algorithm. An attacker can intercept traffic and quickly use dictionaries online to decrypt hashes and retrieve passwords. I know again, if you use weak passwords, such as the numbers of the internal telephone number, it will take milliseconds to decrypt such hashes.

Overcrowded negotiations

Before speech, it is also difficult to move through RTP traffic; the RTP packets themselves contain voice information, just like what you say. Once you have collected enough RTP traffic, you can decode it and listen to what Rosmova is doing.

DoS attack (visual service) behind the SIP protocol

Through the use of the SIP protocol and the UDP transport protocol, which does not install previous sessions, an attacker can craft SIP packets and flood the IP telephony server with them. For example, you can bombard the server with packets like SIP CANCEL, which will cause it to interrupt all calls.

Vrazlivosti PZ

VoIP servers, telephones, gateways and softphones are solutions that replace those other security programs. Various DBMSs, computer programming, program connectors, interpreters, modules, operating systems - everyone has critical problems, and information about these problems is published in various sources. elah. become a victim of evildoers, who know about these influences and take advantage of them.

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In the past decade and 21 centuries, our companions have been navigating the expanses of the ocean of light, and I’ll tell you not about my beloved Asterisk, but about the good old office mini-PBXs, which are similar to IP-PBX analogues. And we’ll let you know first, if and for some reason (IMHO) it’s not possible to deal with them.

101 times we talk about the advantages of IP telephony for communication with the outside world, so I won’t be in the middle of the company, however, there is a blog and a bunch of articles.

If you are only planning to create a telephone network in the middle of the company, you have a lot of kilometers of laying telephone wires and purchased equipment - IP-telephony may well be the best choice for you... Otherwise, you already have ?

Disadvantages of the “traditional” solution:

• The price of installation is for 1 port, with proper operation (one pair of cables laid out for 1-2 telephone devices from the PBX directly to the place of installation, with a line to the digital device approximately 150-300 m away, price A TS and boards before it for 1 port, work and spend on the crossover...).
• The cost of service (mostly spent on laying lines when moving to a new location, laying additional lines, the need to reprogram numbers or switch ports when transferring a computer, changing the type of device: analog/hybrid/digital y).
• The PBX configuration and functionality are much less flexible.
• Remote office or warehouse = contacts all through VOIP or even the police.
• A number of inconsistencies with the different devices (analog devices are deprived of many manual functions, and digital ones stand on par with IP phones + are linked to the telephone exchange of the telephone operator).
• “Hybrid” devices from LG-Nortel and Panasonic deserve a bad word. Use 2 pairs to connect to 1-2 devices, connect 2-4 memory units (replacement 1 for 1 digital device), and also link to the telephone exchange of the operator (rarely, sometimes – up to one).

Advantages of the “traditional” solution:

• If there is an SCS that is insured for a mobile phone, put the intractable hamsters of office computers behind analog phones - the cheapest possible solution. Plus, when switching to IP-PBX, analog handsets can still be of benefit right away.
• If we are talking about a working system, laid by SCS, then the cost of purchasing a digital device, with the provision of 1 (or ½) payment port, will be a little less, lower IP... until the power supply is absorbed into the capacity of the motherboard.
• Droneless telephones, DECT. IP-analogs are more expensive at least in the morning (although all the advantages of digital devices may be lost).
• Good old fax. I feel like my tomatoes are about to fly. Unfortunately, for a wide exchange of fax messages with subscribers, the position is that of millionaires, in the simplest way... an “analog” pair of the remaining miles from our monopolist. Just one FXS with T.38 or G.711 will not last.

It’s funny that after a lot of work with different solutions, I can’t say: “Everyone is buying IP-ATS!”
So, they stink on the head for the strength and thoroughness of outperforming their superniks, but in a number of cases, if there are close to 50-150 members and the infrastructure has already been formed, leading to a revolutionary transition to a day of IP decisions in the middle And the company is oh so difficult.

How do you respect it?