April 25, 2022

SIP Telephony: Principles of Operation and Overview of Business Opportunities

To exchange multimedia data on the Internet, it is necessary to establish an IP connection between devices. This is possible thanks to the IP (Internet Protocol). SIP-telephony is based on SIP trunking and IP telephony principles of voice information transmission. This article will help you learn SIP telephony basics.

Differences in IP/VoIP/SIP

Through IP protocol, computers, gadgets, servers, and other devices are connected to the Internet. Each device has its unique IP address, which is used for transmitting the information.

VoIP (Voice over IP) is a protocol that allows voice transmission over the Internet. The technology is widely used in services for webinars, webcasts, online calls, games, etc.

SIP (Session Initiation Protocol) is a narrower concept, a type of IP telephony. SIP-telephony works on a client-server-client scheme. Its difference is that it is a dedicated communication protocol, i.e., other technologies are not used for connection with subscribers — only this channel.

Call-tracking services can forward calls from swap numbers to SIP numbers, just like to regular landline or cellular numbers.

How Does SIP Telephony Work

Let’s consider the main features and principles of SIP-telephony.

Working principle

During connection, voice is converted into a digital signal, converted information goes to the gadget or other computer, and devices recognize each other. Then, thanks to the SIP protocol, information again becomes analog so that users can have a conversation through the phone handset and computer headset. The speaker’s message is recorded, compressed, and sent to the recipient in a fraction of a second.

Dialogue participants do not notice the codecs’ work, but the load on the Internet is reduced. Meanwhile, the transmission quality remains high due to the transformation of information from analog to digital format.

Making calls

Different devices can be used for SIP telephony and making calls:

  • A laptop or PC. This requires the installation of a special software client and a headset (headphones with a microphone).
  • A smartphone or another mobile device with OS. A special module is installed on the device where the connection is made. Calls can be made over Wi-Fi or mobile networks.
  • A stationary SIP phone. To use it, one needs a connection to a router.
  • A phone with a connected VoIP gateway. Requires connection to a router.


SIP-telephony technology makes it possible to set up automatic forwarding of incoming calls from SIP to other phone numbers. Due to this, the user can stay in touch with customers at any time.

Integration with business services

SIP-telephony is easily integrated with popular CRM systems, analytics, 1C, and messengers. This allows you to automate many routine processes and communicate with customers conveniently, using voice and text communications.

How to Connect SIP Telephony

Several simple variants of SIP-telephony usage via different devices are available for users. One needs an Internet connection with a speed of over 80-100 kbit/sec on a virtual or physical phone.

Desktop or laptop

This option allows you to get by with a stationary SIP phone emulator (softphone). It’s enough to install the software client on your PC or laptop, connect a headset with headphones and a microphone, and a webcam if you want video communication. After that, you must register with a SIP provider, configure the address of the SIP server, and set a login and password.

Smartphone or tablet

Working with gadgets also requires a special module (on iOS, you can find a free application, on Android, from version 4.0 forward, a standard SIP client is used).

You need to specify an account, user name, login, server address, and password.

This option allows employees to stay in touch even when they can’t be at the computer. Besides, it is suitable for calls in roaming, as it makes them quite cheap.

Stationary SIP phone

A desktop SIP phone is usually used for corporate purposes. In addition to speakerphone, voicemail, call forwarding, and call hold, some devices support audio conferencing and high-quality video calls. Such a phone is connected to the local Ethernet network.

There are also dual-mode devices that can connect to a PBX. When configuring the SIP-server address, login, and password, you may need to enter the Outbound Proxy, Server / Proxy Port, and Transport protocol.

How to Get SIP Numbers

Customer numbers are provided by the service provider, depending on the goals and objectives. Typically, services assign customers a number combination — ID, allowing free calls within the network. You’ll need a URI (ID + provider’s address) to communicate with other networks.

Why Choose SIP Telephony

Internet calls are less expensive and more practical than standard telephony. It is possible to solve several business tasks simultaneously if you use Internet calls. Besides, this variant has obvious advantages in comparison with standard telephony.

You can quickly telephone a company without spending money purchasing expensive equipment, wiring, and connecting (it is usually free). Subscription fees are also usually low.

SIP telephony allows for organizing cheap corporate communication and, for example, remote call-centers. Technology allows you to record and prioritize calls and evenly distribute the load on the call center.

Fast connectivity

Connection takes from a few hours to 1 working day. Your service provider configures all your settings.


SIP-telephony allows you not to be tied to an office and stay in touch regardless of access to a working computer, city, or country you are in. With an installed softphone supporting the calling function, you can call from a PC, landline, specialized phones, and gadgets.


Numbers working via the SIP protocol have an unlimited number of lines. Thanks to this, clients are always dialed on the first try.

High quality of communication

Due to continuous improvement of algorithms and the introduction of new protocols and technologies, the SIP protocol ensures high-quality communications if you have a stable 80-100 kbit/sec Internet connection. You can achieve this by switching from Wi-Fi to mobile networks.

Бесплатное стоковое фото с macbook, адвокат, бизнес


Modern communication systems, products, and services, including SIP telephony, can help small and medium-sized enterprises conduct business, increase sales, promote services, and improve business efficiency. Having read this article, you know SIP telephony basics. There’s just one more step before you: start using this helpful technology.

About the author 

Elle Gellrich

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