Describing what is VoIP along with VoIP Network Components.

What is VoIP?

VoIP stands for Voice Over IP.  It is a relatively new communication technology that enables making and receiving voice calls over the existing packet-based Internet Protocol network.  To make a voice call using VoIP, a device should connect to the IP network with a microphone and speakers. Your laptop or phone is one of the example of a device that may use VoIP for voice calls. There could be a video call also possible from a VoIP phone.

What is VoIP diagram

There are many software application examples of VoIP clients, that you may be using newer IP-based telephony. E.g., making a voice call using Facebook or skype using a phone or desktop is an example of a VoIP call.  This software uses VoIP for making and receiving voice calls over the Internet Protocol.

Network components in VoIP technology:

VoIP Network Elements

To enable VoIP communication over the IP network. There have been additional components that have been developed. The following is the list of network components for VoIP.

Soft or IP Phone as a VoIP client:

The software on a PC or on a mobile device to send or receive calls.  There can be dedicated IP phone hardware also.


The IPPBX is a device that is mainly used in call centers for bulk calling using SIP trunking.  It is the hardware and software for VoIP.

VoIP to PSTN gateway:

The gateway does the bridging between traditional PSTN and VoIP networks.

VoIP proxy:

The VoIP proxy works as a router for VoIP signaling and media.

What do I need, to use VoIP? 

To connect to a VoIP network, the first thing is the softphone.

A softphone can be real hardware that implements the actual protocols and applications for communication over an IP network.  Or it can be the only software that can run on a mobile device or a PC. Skype, WhatsApp, etc. are examples of mobile apps that use VoIP. These apps use their respective servers.  For desktop X-Lite and other softphones are the options. These phones can work with a VoIP provider.

Next is the VoIP account from a VoIP service provider:

A VoIP connection provider issues a user name, password, phone number, and address of the server.  A softphone needs to configure the setting in the phone to use the service.  After settings, the phone registers itself with the provider.  If all is fine, then the softphone gets connected and ready to make and receive calls.

To initiate a call, the phone user dials a number, as it dials on any gsm phone. The call reaches the server, and from dialed digits, the outgoing route is decided.  If the call is towards another VoIP number, the call uses only the internet. If the call is to a mobile or PSTN, then VoIP to GSM gateway comes on the way.

We can also understand how VoIP works, with the example of skype. Skype is the most common voice-over IP service across the globe. A person needs to download and install skype software on a PC or mobile device. To use the service requires creating an account on skype.  When a user sign-in, the client registers to the skype server and use sees that its status is online.  A chat or a voice/video call can be started with a contact added.

Analog to VoIP converter :

VoIP to PSTN gateway :

VoIP Protocols:

In the communication world, nothing works without communication protocols.  The following is a list of the most commonly used.






Example protocol stack in VoIP phone:

IP->UDP->SIP/RDP->VoIPPhone with GUI

VoIP Projects:


Asterisk is an open-source IP-PBX.  Provides call center solutions for an organization.  The software supports E1/T1 Bri/Pri and VoIP lines.  In Asterisk, internal phones are configured as an extension. The external line could be VoIP or an E1/T SS7 BRI/PRI line.

An Open source project for developing VoIP applications in the Browser.