IP telephony - what is it? IP telephony: what is it and how does it work Telephone IP

IP phones with a large selection of technical and functionality for large organizations, call centers and individuals. The store’s assortment is designed to accommodate projects of any complexity to effectively staff companies. Each product is a product from proven and reliable global manufacturers, adapted to solve specific hardware problems.

Selecting an IP SIP VoIP phone

Factors to consider when choosing a phone model include:

1. Compatibility of the IP phone for the office with the current one or the provider.

Support for SIP protocol and codecs: G.711. G.722. G.723. G.729 is used by many IP telephony providers. Accordingly, working models of VoIP phones are selected for them.

By collaborating with providers that adhere to the following protocols: SCCP. MGCP. H.323, find modifications that meet their conditions.

2. Number of SIP accounts and simultaneous conversations.

The class of technical parameters in this category depends on the responsibilities of full-time employees and management personnel of the company. For an ordinary specialist, 1 - 2 SIP accounts are enough. A department manager who needs to simultaneously conduct 6 or more independent telephone conversations using a single basic IP unit should buy a SIP phone that supports such functions.

3. Communication ports.

A Gigabit Ethernet port is needed for a high-speed network. IP phones with two ports are needed if users combine the services of a SIP provider and the use of wired telephone pairs.

Other options.

Among the technologies that allow access to the Internet or another IP network, the IP telephone has occupied an important position for several decades now. This device allows you to conduct international conversations online, send faxes, and receive data from the global network.

Buying an IP phone from an online store website in Moscow seems to be a convenient opportunity. We present models from world famous brands Panasonic, CISCO, Siemens, HUAWEI at reasonable prices, since we receive them directly from production lines.

Features of IP telephony

To organize telephone communications over such a network, gateways are used. Each of them is connected either to the device directly or to the PBX line. Thus, communication can take place between two users connected to the gateways without delay, even if they are located on opposite points of the globe. The most convenient thing is that the price of IP telephone services is also quite acceptable: you only pay for the time spent on the network. Therefore, in order to obtain a fast IP connection, telephony is used not only for international calls, but also for a corporate LAN.

IP connection principle

When the gateway receives a signal from the phone, it quickly digitizes the data, compressing it to a size suitable for transmission. The data is then divided into packets and sent over the IP network to the destination. Where the mirror principle operates: the data is converted back into a voice signal through the gateway, the subscriber hears it in its original form.

IP telephony allows you to:

· Maintain cost-effective communication between subscribers, which is much cheaper than calls at international rates;

· You can add or remove a new IP address at any time;

· No need to pay allocated subscriber line, you can connect branches to a common data network;

· Full duplex connection, in which both subscribers can talk at the same time;

• The quality of communication remains at a high level.

There are many benefits from purchasing IP telephony, especially if departments or persons located in different cities have to communicate frequently. But this technology requires good equipment...

In short, an IP phone is a telephone device that uses the IP protocol.

What is an IP phone

Unlike the classic analog telephone, which was invented in the 19th century and uses analog signals, IP phones use IP packets encrypted using various codecs to transmit data. For IP phone operation a necessary condition is a connection to an IP data network, such as the Internet or Ethernet.

Terminology

First, let's define the terminology. Nowadays it is common to use several terms such as IP phone, VoIP phone, SIP phone or Digital phone. They are all true in their own way, but still have some differences.

IP phone– the general and most popular designation, which indicates that the phone uses the IP protocol.

VoIP phone– a fairly frequently used designation when talking about a phone designed to work in a VoIP environment. Essentially, IP phone and VoIP phone are synonymous.

SIP phone– clearly indicates phones using the SIP protocol. All SIP phones are IP phones and VoIP phones, but not vice versa.

Digital phone. Sometimes referred to as a System Telephone. Typically digital or system phones are devices that use proprietary IP protocols. Digital phones can be found from manufacturers such as Panasonic, Samsung, LG-Ericson, Avaya, etc.

As you can see, the main distinguishing point in terminology is the protocol used, so let’s dwell a little more on the protocols for voice transmission.

Protocols and codecs in IP telephony

IP telephony uses special protocols that describe the basic procedures for voice transmission, connection establishment, call termination and other commands. As a rule, an IP phone uses one protocol, but there are exceptions when the devices support two or three protocols at once.

The most popular VoIP protocols are:

• SIP (Session Initiation Protocol)- The SIP protocol is based on open standards and is by far the most popular IP telephony protocol. The SIP protocol is used on most IP phones, VoIP phone systems and services. supported by the vast majority of VoIP phone systems and services.
• I AX2(Inter-Asterisk eXchange protocol) - data exchange protocol in the Asterisk IP-PBX environment. IAX2 was specifically developed by Digium for use with the Asterisk IP telephony server and to solve various problems that arise when using the SIP and H.323 protocols. Today IAX2 is used quite rarely.
• H.323– a fairly old protocol that is used at both the operator and client levels, for example in Avaya and Addpac telephone systems.
• SCCP (Skinny Client Control Protocol) - is the property of Cisco and is used in Cisco IP phones to work with the platform Cisco CallManager.
• MGCP- the oldest carrier-level protocol, which is widely used to organize distributed data transmission systems. Typically used in voice and media gateways.

CodecsIP-telephony

To communicate over IP networks, it is necessary to convert the voice signal into a digital stream. This problem is solved by voice codecs, which are responsible for encoding voice at the input and decoding at the output. Voice codecs determine the audio quality and bandwidth required to send IP packets. There are narrowband codecs that require less bandwidth and wideband codecs. providing better sound quality, but requiring a wider bandwidth. A VoIP phone typically supports multiple voice codecs. The most common speech codecs are presented below:

• GSM- 13 kbit
• Ilbc- 15 Kbit
• G.711- 64 kbit
• G.722- 48/56/64 Kbit
• G.726- 16/24/32/40 kbit
• G.728- 16 kbit
• G.729- 8 Kbit

Types of IP Phones

A classic desktop device that can be found in almost any office.

IP phonewith headset– telephone for call center operators who do not need to use a handset, using only a telephone headset.

– IP phone equipped with a camera, screen and the ability to make video calls.

WirelessDECT telephone(Base + handsets) – a cordless telephone consisting of a DECT base and one or more cordless handsets linked to the base station via the DECT protocol.

– a set of DECT base stations and cordless handsets united into a single network, capable of operating anywhere within the system’s coverage area. The main difference between microcellular systems is the possibility of seamless communication, in which the user moves between base stations without losing voice communication.

WirelessWi-Fi phone- a wireless IP handset that uses the Wi-Fi protocol for connection.

– telephone set for working in conference rooms. A conference phone typically has a dish form factor and is a high-quality hands-free device.

– a device made in the form of a calling panel. Can be equipped with a display, one key or numeric keypad, video camera and card reader.

– USB audio device, made in the form of a handset with a keyboard. Used in conjunction with a softphone on a PC.

(softphone) – software that turns any computer, tablet or smartphone into an IP phone.

IP phones by application type

Each IP phone can be used in different situations and solve different problems.

• Employee phone number- a classic telephone with one or two lines.
• Operator phone– as a rule, a telephone with support for two or more telephone lines with the ability to use a headset.
• Secretary's phone– a telephone with a large number of lines and BLF keys to track employee status and quickly transfer calls. Additional keyboard expansion modules are often used for the secretary's telephone to cover the entire company's personnel.
• Manager's phone number- telephone higher level. Such a phone should emphasize the status of its owner and be qualitatively different from a regular device. The manager's phone can be equipped with an improved elegant case, a large color display, a camera for video calls, a high-quality speakerphone for hands-free calling, and a keyboard expansion module for tracking employee statuses.
• IP phone for hotels and hotels. B&Bs use phones with a minimum set of functions, which have protection against damage and support for special functions for hotels.
• SpecializedIP phones. Devices designed to work in various enterprises or in special conditions. For example, explosion-proof, waterproof or vandal-proof devices.

CharacteristicsIPphones

Among the main characteristics and functionality of IP phones, it is worth noting the following:

• Number of lines. The number of simultaneous SIP (or other) registrations that allows you to receive two or more calls simultaneously.
• Availability of backlit BLF keys for tracking subscriber status and working with quick functions
• Keyboard expansion module support
• Supports various VoIP protocols and voice protocols
• Wideband audio support (HD audio)
• Availability and quality of speakerphone
• Availability and quality of display (size, color, Touch Screen support)
• Availability and quality of camera (for video phone, intercom)
• Number of connected handsets and simultaneous calls (for cordless phone)
• Supports various phone functions such as voicemail, call transfer, do not disturb, conference calling, etc.
• Support for VPN and other technologies that provide a secure connection
• Supports wired headset and EHS – remote call control via wireless headset. Support for Bluetooth headsets.
• Number of network ports, PoE support, Gigabit Ethernet support
• Wireless connectivity (DECT, Wi-Fi)
• Angles of installation of the device on the table, possibility of wall mounting
• Case color

All of the above features and characteristics of IP phones will help you better navigate the variety of devices presented on modern market. When choosing an IP phone, try to accurately define the tasks and select equipment according to your priorities.

Many people ask the question of how to find out the IP address of a phone (smartphone) or computer.

In fact, the IP address is not assigned directly to a computer or phone, but is determined by the point at which these devices connect to the Internet.

IP addresses are assigned to network nodes that participate in the transmission of information. They provide data exchange using a specially developed Internet protocol, hence the name - IP (Internet Protocol).

Therefore, depending on the connection point to a particular network node, the addresses of the same electronic devices may change.

Connect from home.

If you have entered into a home contract with your Internet provider providing you with a static IP address, then you are assigned a specific connection point (the provider’s network equipment with a specific IP address is reserved (only for you), and the address remains unchanged).

If you did not discuss this issue with your provider when drawing up the contract, then you most likely have a dynamic IP address at home. That is, when you connect to the network, you get the nearest free Internet access point on your provider’s equipment. In this case, your IP address may change from connection to connection. It will not be a constant value.

But at this particular moment, all your home devices (computers, laptops, smartphones) will access the network from the same IP that you received during the current connection. Now almost everyone at home has their own WiFi, which provides this.

We connect from the cafe.

Let's say you come to a cafe with your smartphone or tablet. There you get, through the local WiFi, access to another Internet connection point (with a different IP address, which is determined by the cafe’s agreement with its provider).

Of course, all visitors to the cafe will have the same IP address for connecting to the network as long as they access the network from this public establishment.

Mobile Internet.

Likewise, if you have mobile Internet, then depending on your location, you connect to one or another nearest entry point to your mobile operator’s network.

Thus, the IP address you receive is determined by the connection point. And you can use it to track where you are geographically.

Therefore, the IP address of a computer or phone (smartphone) is not a constant value, but depends on the location of the connection to the global network.

We connect not directly, but through a proxy server.

If your IP address is blocked by a site, then you can get to it through a proxy server, which will be an intermediate link and provide access to the blocked site.

A proxy helps you change your IP address. You connect to the proxy's input with your address, and at the output you receive another one. This way you can bypass the blocking.

You can find proxy servers that provide this feature by searching for the phrase “give access” or “proxy server.”

In this case, when you visit a site, the address of the selected proxy server will appear, and you will remain as an anonymous visitor.

The mobile phone (smartphone) can automatically connect through a proxy.

If you, while at home, connect to the Internet via home WiFi from your mobile phone (smartphone), using a mobile browser, for example Opera, then the connection in this case is also automatically made not directly, but through the proxy server of the mobile browser.

You can determine the IP address of your phone or computer using Yandex by typing 2 words in the search bar: “my IP”.

If Yandex immediately shows your IP address, then most likely you are connected directly, without a proxy.

In the case of a smartphone (and the Opera mobile browser, as in my case), after I typed “my IP” on the phone in the search, they didn’t immediately show it to me, but suggested using one of the sites (you can choose from the list).

IP telephony is telephone communication over the Internet, and not through conventional 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 enmeshed the Earth long before the Internet.

The difference between IP telephony and analog telephony is the absence of a traditional cable and telephone set. True, there are options for IP telephony that are outwardly indistinguishable from conventional telephone communication, with familiar devices and wires. Communication is carried out through devices with direct access to the Internet. This 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 analogue telephony or cellular communications.

This telephony is especially popular in offices, opening up opportunities for significant savings. After all, office workers do nothing but call the company’s clients, contractors, and for other reasons.

It is important that communication costs are reduced regardless of which region of the country or other state the connection is made with, because for the Internet, unlike regular telephone communications, there are no state or national borders. Simplicity of configuration and a sufficient level of security makes it possible for IP telephony to compete adequately with analog telephony, gradually displacing it for corporate needs.

At the household level, IP telephony was once quite widespread in the form of cards for long-distance and international communications.

Having purchased such a card for relatively little money, access to the servers of the company providing access to IP telephony was opened from a regular home phone. The numbers for dialing to the servers were published on the card, and then, according to the usual rules for dialing a long-distance or international number, it was possible to call another subscriber, but via the Internet, and not via a telephone line. And the telephone line was used in this case at the cheapest rate: in the section between the phones 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. Once at the recipient's address, the transmitted information is decoded back, acquiring the format of a familiar voice signal. All this happens in a matter of seconds, thanks to which information is transmitted in real time without loss of broadcast quality.

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

Connecting and setting up IP telephony

To use the technology, you also need the appropriate equipment: routers, routers, servers, etc.

A software connection to IP telephony involves installing, on a laptop or gadget, an appropriate application that supports communication via a protocol that ensures the operation of IP telephony.

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

The history of IP telephony

It became possible to transmit audio and video files, text messages over the Internet via ISDN. But this program did not find a response, since it worked very slowly and until 1995, innovative developments were not carried out in this direction.

Then the first example of Internet telephony from the Israeli company VocalTec appeared. But it worked one-way, on the principle of walkie-talkies, requiring identical software from the users between whom the connection was made. It was also quite common at that time for data to be lost during transmission, mainly due to the low speed of the Internet at that time.

Towards 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, the integration of telephone networks with the so-called “packet” networks, in fact with the Internet networks, took place, which became possible thanks 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 led to a long-term loss of interest in this area.

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 implemented. After another 3 years, with the help of a new VoIP router, it became possible to operate telephony without turning on the computer at all.

Since then, the popularity of IP telephony has been constantly growing. For ordinary users, it is not of fundamental importance what protocols are used and how they work. Clean communication, additional features and low tariffs are much more important to them.

Advantages 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 worth noting as advantages:

• Accessibility and mobility,

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

This essentially virtual number can be accessed regardless of the geography of its location; all you need is high-speed Internet access. It turns out to be a kind of analogue of mobile communications, only instead of access to mobile networks, access to the Internet is 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 configurations with the introduction of new services.

• Privacy and Security.

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

• Wide range of possibilities,

The use of IP telephony is the optimal solution for offices, enterprises and organizations precisely because of the last point about capabilities.

• Multichannel number functions,
• forwarding of incoming calls,
• voice mail,
• virtual fax and
• blacklisting service

allow you to get the most out of your connection without making any effort.

Most IP telephony services are included in the basic package and are used after paying 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 dramatic 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 money.

Since traffic on the Internet is not geographically referenced, the distance between the region of sending and the region of receiving information also does not play a role, unlike the usual telephone communication, which works on the principle “the further, the more expensive.” There is no additional charge for sending traffic in any direction.

When calling mobile or landline phones abroad or to other regions, the cost is also an order of magnitude lower than on an analog network. There are no subscriber line fees either, but it’s true that instead you have to pay for using the Internet according to tariffs.

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

IP telephony competitor: Skype

Applications for maintaining telephone and video communications, for example, well, compete quite successfully with IP telephony. Similar applications for computers and mobile devices allow voice and video communication between subscribers also via the Internet, 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 audio and Skype between several Skype subscribers can be free. It is also possible to transmit visual information by “sharing” (organizing collective viewing) one of the computer screens connected to the Skype conference.

IP telephony competitors: mobile operators

In addition, mobile operators do not stand still. They offer their corporate clients so-called virtual telephony. Its essence is that each employee of a corporation (firm) is assigned a short number (3-4 digits), as if it were the 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 telephones connected directly to the company’s servers that provide Internet access.

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

Results

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

And the “old” telephone companies are not standing still, developing their networks and transferring them “to digital” in search of competitive solutions that will allow them to successfully “compete” with IP telephony.