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Voice over IP

Adapted from Wikipedia · Adventurer experience

A close-up of a Gigabyte BRIX single-board computer set up as an Asterisk-based PBX with Cisco IP-phones, showing how technology can be used for communication systems.

Voice over Internet Protocol (VoIP), also called IP telephony, is a way to make voice calls using the Internet. Instead of regular phone lines, VoIP changes voice into data and sends it over the Internet. This lets people make and receive calls using services like Skype, Microsoft Teams, and Google Voice. Regular phones can also use VoIP by connecting to the Internet with special devices.

The terms Internet telephony, broadband telephony, and broadband phone service mean sending voice and other messages, such as fax, SMS, and voice messaging, over the Internet. This is different from the old way of calling, known as the public switched telephone network or plain old telephone service.

VoIP also works on mobile phones through technologies like Voice over LTE (VoLTE) and Voice over NR (Vo5G). These let people make calls using 4G and 5G mobile data, making VoIP a big part of today's mobile world.

Overview

Voice over Internet Protocol (VoIP) is a way to make voice calls using the Internet. Instead of regular phone lines, VoIP turns voice into small pieces of data called packets that travel through the Internet. This can work on many devices, like special VoIP phones, computers, and phones connected with Wi-Fi or mobile data.

VoIP has changed over time. Early services worked like old phones, but newer ones, such as Skype and Google Talk, let people talk to each other easily over the Internet. Now, VoIP is also part of mobile networks like VoLTE for 4G and Vo5G for 5G. This helps people make clear, good-quality calls with their mobile phones and keep their regular phone numbers.

Protocols

Voice over IP uses special systems to let people make voice calls using the internet. Some of these systems are made by companies, and others follow rules that everyone can use. They help manage connections, share calling information, and move voice data.

There are many protocols, or rules, used for VoIP. Some popular ones include Session Initiation Protocol for managing connections, H.323 for controlling calls, and Real-time Transport Protocol for moving audio and video data fast. Other protocols help keep the call safe, clear, and working well.

Adoption

Example of residential network including VoIP

VoIP services let people make phone calls using their internet connection. They work with special VoIP phones, adapters for regular phones, or software on computers. Many companies offer plans with unlimited calling for a monthly fee, and calls between customers of the same service are often free.

Businesses often choose VoIP to save money. It lets them use one network for both phone calls and data, which reduces costs. VoIP systems are flexible and can let workers switch between office and mobile networks without losing calls. These systems have grown to include many types of communication, all managed together.

Delivery mechanisms

Asterisk-based PBX for small business

VoIP systems can be set up in two main ways: private systems or hosted systems from outside companies. Private systems are like old office phones, placed inside a company's own network.

Many people now choose hosted or cloud VoIP systems, especially for small uses or personal needs. These systems are run by a service provider and kept in their own data centers[/w/0]. This means users don't have to worry about fixing things. Users connect to these services using VoIP phones or apps on computers and mobile devices over the internet. Private VoIP systems stay inside the company's own setup. They give more control but need the company to handle fixing and performance. These systems can be physical devices or software and often use local networks or safe private links.

Quality of service

Communication over the internet can sometimes be less reliable than using regular phone lines. This is because the internet does not always make sure that data arrives perfectly. Voice calls sent over the internet, called VoIP, travel in small pieces called packets.

These packets might get lost or arrive out of order. This can make the call sound choppy.

To help with this, special methods can be used. These methods make sure voice packets get through quickly, even when the internet is busy. For example, voice packets can be marked so they move ahead of other less important information. Some technologies help keep voice calls clear by managing how data is sent and received. This makes sure that voice sounds smooth even when the internet is crowded.

Performance metrics

The quality of voice transmission in VoIP can be measured using several important metrics. These include packet loss, jitter, latency (delay), post-dial delay, and echo. These metrics help make sure voice calls sound clear and smooth when using VoIP services.

PSTN integration

A VoIP media gateway controller works with a media gateway to connect voice and data. It links calls made through VoIP to regular phone networks. Modern systems have Ethernet interfaces for these connections.

VoIP systems often use a global numbering standard to route calls between VoIP users and regular phones. They can also use other identification methods, like usernames or email-like addresses, to make and receive calls. Echo can sometimes be a problem. This is caused by differences in older phone circuitry or sound paths in the receiving device.

Number portability

Local and mobile number portability let people keep their phone numbers when switching providers. VoIP providers must follow rules to make sure calls are correctly routed, even when numbers are moved between carriers. This can be complex, especially for calls made to mobile phones on traditional networks.

Emergency calls

Traditional landlines have a direct link between a phone number and a physical location. This helps emergency services find callers. With VoIP, this link isn't automatic because devices can move and use different networks. In the United States, VoIP providers use a system called Enhanced 911 (E911) to connect phone numbers with physical addresses for emergency calls. This system works only if users keep their address information up to date.

Fax support

Sending faxes over VoIP networks is called Fax over IP (FoIP). Early VoIP systems had trouble sending fax documents because the ways they changed voice into digital signals were not good for fax machines.

The T.38 protocol helps solve this problem. It makes sure fax messages can travel over IP networks, even though they work differently from old analog lines. Fax machines can be regular ones connected to an analog telephone adapter (ATA) or special software or devices connected to a network. Some newer high-end fax machines can use T.38 directly and are connected to a network switch or router.

Power requirements

Regular home phones are often connected to special phone lines. These phones can work even if the house power is off. But they can stop working if there is a problem with the phone lines.

VoIP phones and adapters connect to devices like routers or cable modems. These devices need regular house power to work. Some VoIP services have special equipment with batteries. This can keep the phone working for a few hours if the power goes out. If the internet device can't be used, some services can send calls to a cell phone instead.

Security

VoIP calls can be kept safe with special rules called Secure Real-time Transport Protocol. VoIP systems have tools to talk and share online, just like regular phones. They need extra safety steps to keep information private.

VoIP systems can face the same safety problems as other internet devices. Bad people might try to stop service, take information, or hear conversations. Special software and tools can help keep VoIP calls safe, especially for important groups like governments and the military.

Caller ID

Voice over IP systems support caller ID like regular phones do. This means when someone calls you, their number or name can show up on your phone or device. Many VoIP services let you pick what information shows as your caller ID when you make a call.

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Operational cost

VoIP makes talking on the phone much cheaper. It uses the same internet connection for both data and voice. With one broadband connection, you can make and receive many phone calls at once. This saves money compared to regular phone services.

Regulatory and legal issues

As VoIP gets more popular, governments are looking more closely at how to manage it, just like they do with regular phone services.

In some countries, like Panama and Ethiopia, there are strong rules or even bans on VoIP. In Canada, VoIP services must be able to connect to 9-1-1 for emergencies. In the European Union, each country decides its own rules for VoIP, often treating services that use special networks differently from those that use the regular Internet.

In Saudi Arabia, a ban on VoIP was removed in 2017 to help businesses. In the United Arab Emirates, using unofficial VoIP services is not allowed, although some services like Skype were permitted until 2018 when many were blocked. Rules were eased in 2020 because of the COVID-19 pandemic, but popular apps like WhatsApp and FaceTime were still not allowed for voice and video calls.

In the United States, VoIP providers must follow rules similar to regular phone companies. This includes supporting local number portability, making sure services work for people with disabilities, and helping law enforcement when needed.

History

The history of Voice over Internet Protocol (VoIP) began with scientists trying to make voice calls using networks. In the 1970s, they worked on sending voice as small pieces of data. This was hard because the internet was slow. They found ways to make voice data smaller, so it could travel over the early internet.

Over time, many new tools were made to improve VoIP. By the 1990s, companies started selling VoIP software. In the 2000s, popular programs like Skype made VoIP easy for everyone. Today, VoIP is a normal way to make voice calls over the internet, using ideas from the past.

Milestones

Related articles

Internet
Fax
Internet Protocol
SMS
Voice messaging
Public switched telephone network

This article is a child-friendly adaptation of the Wikipedia article on Voice over IP, available under CC BY-SA 4.0.

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