What is VoIP? (What is Voice over Internet Protocol?)

Last Updated on April 8, 2024

Voice over Internet protocol (VoIP) is a telephone technology that allows individuals to receive and make phone calls via the internet as opposed to a traditional phone system or Public Switched Telephone Network (PSTN). In a traditional PSTN, the user is limited to a single analog or proprietary digital telephone at their desk. VoIP allows users to send and receive calls from any VoIP enabled device. This includes any soft phone, laptop, smart phone, tablet, etc.

How does VoIP work?

VoIP Configuration

When a user makes a phone call using VoIP, their VoIP enabled device collects audio (and possibly video) call content and sends it to the recipient’s phone via the Internet and a VoIP service provider. The caller may use any of the following VoIP enabled devices:

Analog Telephone Adapters (ATA) – If the user does not have a VoIP device, a third-party adapter is available. These devices connect traditional analog telephones, fax machines and other analog devices to a VoIP telephony network or digital telephone system to a VoIP telephony network or telephone system. The ATA provides the connection between the analog telephone and the router to transfer the digital data through the internet.

Soft Phones on Computers – These devices use a third-party software application. The software is installed on a desktop, laptop or any personal computer with an internet connection. The application uses the microphone, headphones or speakers for communication.

VoIP phones or devices – These devices may be a smartphone or may appear to look and operate similar to a tradition phone. The difference is, they connect to the internet to make a phone call. Many smartphones may use a third-party application to send or receive calls.

For smartphones, there is a variety of third-party applications available for VoIP communication such as Skype, Facebook Messenger, FaceTime and many more. Some third-party applications for smartphones, such as Skype, have the ability to make calls to PSTN lines. Please note, this feature may include fees. Other features may also include direct calling to another smartphone or VoIP enabled device, video calling and group conferencing.

Pros and Cons of VoIP

Compared to PSTN, VoIP can deliver more features and functionality to the user than PSTN.


  • Simplicity – A single connection to the internet can transmit multiple phone calls. This eliminates the need for multiple physical phone lines, unlike PSTN. This enables VoIP setup to be simpler than PSTN which requires a physical line for each phone connection.
  • Portable – Telephone numbers are portable. The user may take their phone number anywhere and use it as long as there is an internet connection. They simply need to connect their computer, smartphone, or tablet to the internet to access the phone system.
  • Features – VoIP allows businesses to use features such as video conferencing, file sharing and SMS texting which are not available in a PSTN system.
  • Scalable – One of the major benefits of VoIP is the ability to scale easily by simply adding an additional line on demand. This allows businesses to only purchase the lines they need. This is different when compared to ISDN PRI with a maximum of 23 lines which requires the purchase of an additional PRI interface board and PRI line services for extra channels regardless if they are in use.


  • Internet Connection Required – VoIP requires a high-speed internet connection to make and receive calls. If the internet connection is slow, the call quality will be impacted. It is recommended for businesses with a large call center ensure there is sufficient bandwidth to maintain high call quality.
  • Power Outages – Unlike PSTN lines that do not rely on electricity to function, VoIP requires a broadband connection. Businesses typically rely on routers to connect their VoIP devices to the internet. These devices require electricity to function so when there is a power outage at the office, then internet services will be offline and this will impact VoIP services. Businesses may mitigate this risk by retaining some PSTN/TDM trunks for this reason. Other companies may also maintain backup power generators as an electrical source for some routers and VoIP devices in case of a power outage.
  • Security – VoIP is an internet service. This means there is a possible risk for cyber-attacks such as eavesdropping, DOS and more. Businesses should choose a VoIP service provider capable of protecting their systems from such attacks and follow best practices.

Is VoIP Secure?

VoIP phone systems do have security vulnerabilities. Some attacks may occur and be obvious, while some attacks may run silently and be undetected for months.

What are VoIP Vulnerabilities?

There are several types of VoIP security issues. The most common online security threats are listed below.

  • Eavesdropping – When a user initiates an outbound call on a non-secure or unencrypted internet connection, attackers may monitor the call and collect sensitive data.
  • Toll Fraud – When an attacker gains access to a business’ VoIP environment, they initiate long distance calls which may be expensive.
  • Denial of Service – When attackers intentionally flood a VoIP environment with calls to overwhelm and crash the system.
  • Malware – Hackers use malicious software to gain access to a company’s email or phone system through insecure internet connections. This provides the attacker an opportunity to infiltrate and obtain access to sensitive business data.

These are only a few examples and there are many more security risks. Although, it impossible to achieve a completely secure phone system, exercising best practices will limit exposure to online vulnerabilities.

Best Practices for VoIP Security

Companies that exercise the following best practices will lower their risk to exposure from VoIP Security threats.

  • Enforce Secure Passwords – Passwords provide the first line of defense against unauthorized access to a company’s communications systems. Passwords are more effective when they are at least eight characters long, consist of both lower-case and upper-case letters, contain numbers and symbols.
  • Provide employees with security training – The second line of defense against unauthorized access is educating employees. Train employees on how to spot information security risks such as online fraud, phishing, social engineering and other risks. Encourage employees to report any strange behavior to management.
  • Apply updates regularly – A software vulnerability is a security weakness found in a software program. Intruders may take advantage of this weakness by creating code called malware to exploit these vulnerabilities. The malware can then steal data and obtain access to sensitive information. Applying updates may repair security holes or weaknesses found in VoIP devices.
  • Deactivate accounts by employees who have left the company – when an employee leaves the company, it is best practice to deactivate their access to company resources. This prevents former employees from accessing company resources. Intruders may also compromise a former employee’s device and attempt to obtain access to the business.
  • Setup a VPN for remote staff – A Virtual Private Network, or VPN, provides online privacy by creating a private network from an internet connection outside the company. This allows employees to make and receive calls from a secure network even from a public internet connection.
  • Monitor access and call logs – Call history logs typically contain time and date of incoming and outgoing calls and call volume by the company. Business managers may review these logs on a regular basis and if they spot any abnormal activity, they may be able to stop or prevent a security breach.

Businesses will improve their security and minimize the chances of a security breach by implementing these best practices.

Looking towards the future of VoIP

VoIP is the future. Businesses are drawn to the benefits of VoIP such as scaling by adding lines on demand, portability by allowing users to make calls anywhere with a VoIP enabled device with an internet connection and all other communication features that are available in the system. As the adoption of VoIP continues to grow, companies must not forget the security risks that are inherent in an online communications system, choose a VoIP provider and exercise best practices. This will mitigate risk and limit exposure to any online security risks.

Call monitoring may be added to the system to make a VoIP environment more powerful. Call recording allows managers the ability to listen and record live calls. This enables managers to implement coaching and improve the performance of their call centers. To learn more about call recording on a VoIP environment, please see VoIP Call Recording – Record Your IP Calls or contact us to find a call recording solution for your business.

Previous Call Recording Articles:

What is SIP Trunking? How to Record Calls in a SIP Trunk Environment.

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PSTN vs VoIP – How to determine which technology is better for your business.

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Do you have a hosted PBX or cloud VoIP provider? Learn how to take advantage of having your calls recorded and stored locally.

Last Updated on April 8, 2024