A Full Guide to VoIP Security in 2024 – Learn the Best Practices

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As more companies turn to Voice over Internet Protocol (VoIP) to communicate with customers, VoIP security has become a key challenge for many IT managers.

At Techopedia, we appreciate it’s an intimidating task to ensure the confidentiality and integrity of your company’s voice interactions when the risks of data breaches and eavesdropping loom large.

In this article, we guide you through the complexities of VoIP security so you can confidently take advantage of this technology in your business. We cover the most prevalent vulnerabilities of VoIP and provide practical strategies to fortify your systems.

Key Takeaways

  • VoIP security is a multifaceted challenge that requires encryption, network defenses, and user education to protect against various threats.
  • Regular updates and vigilant monitoring are key to maintaining a secure VoIP environment and promptly addressing vulnerabilities.
  • Choose a secure VoIP provider carefully, considering their security protocols, compliance standards, and infrastructure.
  • VoIP security also involves implementing policies and training to foster a culture of security awareness.
  • Despite the complexities, securing VoIP systems is essential for safeguarding business communications and ensuring operational continuity.

VoIP and Internet Security in 2024

Voice over Internet Protocol (VoIP) is a technology that allows voice communication to be conducted over the Internet. Unlike traditional telephony, VoIP converts voice into digital packets that are transmitted over IP networks.

This method of communication can be more efficient and cost-effective but introduces a range of security concerns. Since these voice packets travel across the public Internet, they’re vulnerable to:

  • Interception
  • Unauthorized access, and
  • Manipulation

VoIP systems can be compromised in various ways, from eavesdropping on conversations to sophisticated attacks that disrupt service or lead to financial fraud.

The security of your VoIP system is only as strong as the measures you put in place to protect it. Understanding the technology’s inherent vulnerabilities is the first step in creating a robust defense.

13 Common VoIP Security Threats and How to Deal With Them

In the following sections, we address the most dangerous types of VoIP security attacks and offer advice on preventing, avoiding, or minimizing them in your VoIP system.

Whether it’s eavesdropping, call hijacking, or denial of service attacks, you’ll learn the best practices to secure your voice communications in 2024.

1. VoIP Eavesdropping

Our first concern is eavesdropping. VoIP eavesdropping is a security breach where an attacker intercepts VoIP calls to capture audio data. This threat exploits vulnerabilities in VoIP infrastructure, allowing unauthorized listeners to access sensitive information.

How to Prevent Eavesdropping on VoIP

To safeguard against VoIP eavesdropping, you should:

  • Encrypt voice data using protocols like Transport Layer Security (TLS) and Secure Real-Time Transport Protocol (SRTP), making it indecipherable to eavesdroppers.
  • Strengthen network security with firewalls and Intrusion Detection Systems (IDS) that can identify and block suspicious activities.
  • Implement Virtual Private Networks (VPNs) for secure communication channels, crucial for remote employees or when using public Wi-Fi.
  • Consistently update VoIP applications and hardware to patch existing security loopholes that could be exploited for eavesdropping.
  • Educate team members on safe communication practices, emphasizing the importance of security when discussing sensitive information.

2. Packet Sniffing

This is a technique attackers use to capture data packets from a network. For VoIP, this can mean the unauthorized capture of voice packets, potentially reconstructing entire conversations and posing a significant threat to privacy and confidentiality.

How to Prevent VoIP Packet Sniffing

To combat VoIP packet sniffing, consider these actions:

  • Encrypt all VoIP traffic end-to-end, ensuring that captured packets can’t be easily interpreted by sniffers.
  • Use network security tools to monitor for signs of packet sniffing and to secure your network perimeter effectively.
  • Enforce strict access controls to limit network access to authenticated users and devices.
  • Regularly perform network security audits to identify and mitigate risks that sniffers could exploit.
  • Train your team on recognizing and responding to security threats, including the risks associated with packet sniffing, to encourage a culture of security awareness.

3. VoIP Call Hijacking

VoIP call hijacking is an attack where perpetrators take control of a call session. Without robust security measures in place, digital signals can be intercepted and manipulated.

How to Prevent Call Hijacking on VoIP

To mitigate the risk of VoIP call hijacking, you should:

  • Implement strong user authentication methods, such as multi-factor authentication, to verify the identity of users before granting access to VoIP services.
  • Use secure and regularly updated session border controllers (hardware devices that regulate the flow of IP communications) to manage all call traffic.
  • Use encryption protocols to prevent unauthorized interception and manipulation of call setup information.
  • Regularly review and update access control lists and session initiation permissions to restrict call handling to authorized devices and networks.
  • Conduct regular security audits and penetration testing to identify and address vulnerabilities that could be exploited for hijacking purposes.

4. Caller ID Spoofing

Caller ID spoofing involves altering the caller ID to misrepresent the origin of a call. For VoIP, this can be used to deceive recipients into thinking a call is from a trusted source, potentially leading to fraud or phishing attempts.

How to Prevent VoIP Caller ID Spoofing

To prevent caller ID spoofing in VoIP systems, implement these strategies:

  • Use authentication methods like Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted information using toKENs (SHAKEN) protocols to validate caller ID information.
  • Establish policies that require user verification before sensitive information is discussed or transactions are approved, even if the caller ID appears legitimate.
  • Employ network-level analytics to detect patterns indicative of spoofing, such as frequent short-duration calls from the same number.
  • Educate your team about the risks of caller ID spoofing and establish procedures for reporting and responding to suspected incidents.
  • Work with your VoIP service provider to ensure they have robust mechanisms in place to identify and block spoofed calls.

Related: 9 Common Phishing Scams and How to Protect Yourself

5. Toll Fraud and Service Theft

Toll fraud and service theft in VoIP occur when attackers gain unauthorized access to a company’s VoIP system to place calls without consent, often resulting in substantial unauthorized charges.

How to Prevent Toll Fraud on VoIP

To protect against toll fraud in your VoIP system, consider these preventative measures:

  • Implement strong password policies and change default credentials for all VoIP equipment and accounts.
  • Use access control lists to restrict calling capabilities to authorized users only—especially to high-cost destinations.
  • Regularly monitor call logs for any unusual activity, such as calls to unfamiliar numbers or spikes in call volumes, particularly outside of business hours.
  • Set up automatic alerts for abnormal calling patterns or usage, which could indicate fraudulent activity.
  • Limit call forwarding and transfer capabilities to reduce the risk of unauthorized use of these features for toll fraud.
  • Work with your VoIP provider to block calls to high-risk destinations known for toll fraud.

6. Denial of Service (DoS) Attacks

Denial of Service (DoS) attacks on VoIP systems aim to overwhelm the network or service, rendering it unavailable to legitimate users. These attacks are disruptive to VoIP because they can lead to dropped calls, degraded call quality, and complete service outages.

How to Prevent VoIP Denial of Service (DoS) Attacks

To fend off DoS attacks on VoIP systems, follow these steps:

  • Deploy network security measures, such as firewalls and intrusion prevention systems, specifically designed to handle VoIP traffic.
  • Configure rate limiting and bandwidth shaping to control the flow of data and prevent network overload.
  • Establish redundancy with failover capabilities to maintain service continuity in the event of an attack.
  • Keep your VoIP infrastructure updated to mitigate vulnerabilities that could be targeted by DoS attacks.
  • Use a comprehensive monitoring system to detect early signs of a DoS attack and respond quickly.
  • Consider employing a managed security service provider (MSSP) that specializes in real-time DoS attack mitigation and can absorb or deflect malicious traffic.

7. Man-in-the-Middle (MitM) Attacks

Man-in-the-Middle (MitM) attacks in VoIP occur when an attacker intercepts and alters the communication between two people. Attackers could capture or manipulate sensitive information, such as login credentials, without the users’ knowledge.

How to Prevent Man-in-the-Middle (MitM) Attacks on VoIP

To protect your VoIP communications from MitM attacks, you should:

  • Use strong end-to-end VoIP encryption for all calls to prevent attackers from deciphering intercepted data.
  • Employ TLS to secure the signaling data and ensure the integrity of the communication.
  • Implement certificate-based authentication to verify the identity of the communicating parties and prevent impersonation.
  • Keep your network equipment firmware and software updated to patch known VoIP vulnerabilities that could be exploited in MitM attacks.
  • Educate your team on secure communication practices, such as avoiding unsecured Wi-Fi networks for VoIP calls, which are more susceptible to MitM attacks.

8. Malware and VoIP Software Vulnerabilities

Malware and software vulnerabilities present a risk to VoIP systems when malicious actors exploit weaknesses to disrupt operations or steal data. This could mean unauthorized access, data breaches, or compromised call functionality, making it a critical security concern.

How to Prevent Malware and VoIP Software Vulnerabilities

To prevent malware and protect against VoIP software vulnerabilities, follow these guidelines:

  • Ensure all VoIP-related software is regularly updated with the latest security patches to close off potential entry points for malware.
  • Install reputable antivirus and anti-malware solutions on all devices that interact with your VoIP system.
  • Implement a strong network security policy, including the use of firewalls and intrusion detection systems, to monitor and prevent malicious traffic.
  • Conduct regular security audits and vulnerability assessments of your VoIP infrastructure to identify and address potential weaknesses.
  • Train employees on the importance of safe browsing habits, email security, and the dangers of downloading unauthorized software, which could introduce malware into your VoIP system.

Related: How to Protect Your Online Privacy: 7 Practices To Implement

9. IP Network Vulnerabilities

IP network vulnerabilities are security flaws within the network infrastructure that can be exploited to attack VoIP systems. This can lead to unauthorized access, data breaches, and service disruptions, compromising the confidentiality of voice communications.

How to Prevent IP Network Vulnerabilities

To prevent IP network vulnerabilities in your VoIP system, take these steps:

  • Regularly update routers, switches, and other network devices with the latest firmware to address known security vulnerabilities.
  • Segment your network using Virtual Local Area Networks (VLANs) to isolate VoIP traffic from other network traffic, reducing the attack surface.
  • Conduct periodic penetration testing and network assessments to uncover and remediate potential security weaknesses.
  • Employ network security devices like firewalls and intrusion detection/prevention systems to monitor and protect against malicious activities.
  • Implement strict access controls and authentication protocols to ensure that only authorized users and devices can access the VoIP network.

10. S.P.I.T. (Spam over IP Telephony)

S.P.I.T., or Spam over IP Telephony, is the VoIP equivalent of email spam, where unsolicited bulk messages are delivered via VoIP calls. This threat is concerning for VoIP users due to the potential for disruption and the delivery of phishing or malicious content.

How to Prevent S.P.I.T.

To combat S.P.I.T. in your VoIP system, consider the following measures:

  • Deploy anti-spam solutions that specifically target VoIP platforms to identify and block unwanted calls.
  • Implement call screening and blacklisting features to prevent known spammers from reaching your network.
  • Use CAPTCHA mechanisms on VoIP systems that require callers to prove they’re human before the call is connected.
  • Educate your team about the nature of S.P.I.T. and encourage them to report any suspicious calls they receive.
  • Work closely with your VoIP provider to leverage their expertise and resources in identifying and mitigating S.P.I.T. threats.

11. Vishing

Vishing, or voice phishing, is a fraudulent practice where attackers use VoIP to impersonate legitimate entities and extract individuals’ personal, financial, or security information.

How to Prevent Vishing

To prevent vishing on your VoIP system:

  • Educate your team about the nature of vishing attacks and the importance of not sharing sensitive information over the phone without verification.
  • Establish verification procedures for requests for sensitive information made during VoIP calls, such as a follow-up email or using a pre-agreed passphrase.
  • Implement caller ID verification technologies like STIR/SHAKEN to help authenticate incoming calls and reduce the effectiveness of vishing attempts.
  • Encourage employees to report suspected vishing calls to your IT or security team for investigation.
  • Regularly review and update security protocols for VoIP communication to ensure they address the latest vishing strategies.

12. VoIP Call Tampering

VoIP call tampering is the deliberate manipulation of VoIP call data. Attackers may inject noise, drop packets, or alter the communication stream, leading to degraded call quality or misinformation. This disrupts business operations and the integrity of the calls.

How to Prevent VoIP Call Tampering

To protect against VoIP call tampering:

  • Use encryption protocols like Secure Real-Time Transport Protocol (SRTP) to protect the integrity and confidentiality of voice data packets.
  • Implement Quality of Service (QoS) measures to prioritize VoIP traffic and reduce the chances of tampering that can cause call degradation.
  • Use network monitoring tools to detect anomalies in VoIP traffic that may indicate tampering attempts.
  • Establish a secure and resilient network infrastructure with redundancy to minimize the impact of any tampering.
  • Train your staff to recognize signs of call tampering, such as unexpected call quality issues or strange noises during calls, and report them promptly for investigation.

13. V.O.M.I.T. Attacks (Voice over Misconfigured Internet Telephones)

V.O.M.I.T. attacks exploit misconfigurations in VoIP systems, such as improper system setup or overlooked security settings, to eavesdrop on conversations or extract call data. This can lead to significant privacy breaches and information leakage.

How to Prevent V.O.M.I.T. Attacks

To protect against V.O.M.I.T. attacks:

  • Conduct regular comprehensive audits of your VoIP configuration settings to ensure they align with the latest security best practices.
  • Change default passwords and disable unnecessary services on VoIP devices to minimize vulnerabilities.
  • Implement strict access controls and network segmentation to limit exposure of VoIP infrastructure to potential attackers.
  • Train IT staff on proper configuration and ongoing management of VoIP systems to prevent misconfiguration-related vulnerabilities.

How to Choose a Secure VoIP Provider

Selecting a secure VoIP provider is crucial for protecting your business communications. Follow these steps to ensure you choose a provider that prioritizes security and reliability:

  1. Research the Provider's Reputation

    Start by researching the reputation of potential VoIP providers. Look for reviews, testimonials, and case studies. A platform with a strong track record is more likely to offer a reliable service.
  2. Verify Security Protocols

    Inquire about the security protocols each provider uses. A secure VoIP provider should offer end-to-end encryption, such as TLS and SRTP, to protect your calls from eavesdropping and tampering. It should also have robust network security measures in place, including firewalls and intrusion detection systems.

  3. Assess Compliance Standards

    Check if the provider adheres to industry-standard compliance regulations, such as GDPR, HIPAA, or SOC 2. Compliance with these standards indicates a commitment to protecting user data and maintaining privacy.

    Related: Comply and Protect: The Data Security Rulebook

  4. Evaluate Infrastructure and Redundancy

    A secure Internet service provider should have a resilient infrastructure with redundancy built in to prevent service disruptions and data loss. Ask about their data center locations, backup systems, and disaster recovery plans.
  5. Understand Authentication and Access Controls

    Determine what authentication methods the provider supports. Multi-factor authentication (MFA) and strong password policies are vital for preventing unauthorized access to your VoIP system.
  6. Consider Transparency and Support

    Choose a provider that’s transparent about their security practices and offers responsive customer support. You should have access to a knowledgeable team that can assist with any security concerns or incidents.
  7. Look for Regular Updates

    Ensure the provider regularly updates its systems to address new vulnerabilities. It should have a clear patch management policy to keep its services secure against the latest threats.

    Related: Why is Patch Management so Important in Cybersecurity?

  8. Request a Trial Period

    Before committing, request a trial period to test the service in your own environment. This will allow you to evaluate the provider’s security features and ensure they meet your business needs.
  9. Compare Costs and Features

    Finally, compare the costs and features of the providers you’re considering. While security should never be compromised for the sake of cost, finding a provider that offers the best value for your investment is essential.

More information: The Best VoIP Services in 2024


With the rapid move to VoIP communication, VoIP security is an essential defense against a number of threats that can compromise your business operations and privacy.

We’ve explored common vulnerabilities and threats to VoIP services and best practices to mitigate them. Maintaining the integrity and confidentiality of VoIP communications requires a proactive approach.

This means combining robust security measures, continuous monitoring, and a culture of awareness. As VoIP continues to evolve, so too should the strategies to protect it, ensuring that businesses can leverage VoIP’s benefits without the potential risks.


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Richard Sutherland
Technology Expert
Richard Sutherland
Technology Expert

Richard brings more than two decades of computer science, business operations, and full-stack development experience to Techopedia. A Computer Science graduate and former Samsung IT support manager, Richard has taught courses in Java, PHP and Perl, and created code for the public and private sectors. A prolific B2B and B2C tech writer, Richard has worked for Samsung, TechRadar Pro, and more.