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VoIP Security How It Works, Threats, and Best Practices

a person checking voip security and encryption

VoIP phone systems are becoming more popular among businesses of all sizes for their cost efficiency, ease of use, and overall quality. However, many underestimate the holes in VoIP security. Despite its apparent benefits, VoIP security is a genuine cause of worry—but there are ways to mitigate VoIP security risks.

Even though cybercrime persists, VoIP encryption can go a long way in keeping your data secure. Learn why VoIP security systems matter, how they work, and how to employ best practices.

Why is VoIP Security Important?

VoIP security ensures the confidentiality of voice data, preventing eavesdropping and unauthorized access to sensitive information. Maintaining this integrity prevents tampering and manipulation during transmission.

Because VoIP security systems protect against cyberattacks like DoS and DDoS, they ensure availability and prevent downtime.

Through authentication measures, businesses can verify user and device identities, preventing unauthorized access and fraud.

Top VoIP Security Threats

Unfortunately, no device is 100% protected from cyber threats. Below are the most prominent security threats to VoIP systems.

  • Eavesdropping and call Interception: Attackers can intercept VoIP calls and eavesdrop on conversations, compromising the confidentiality of sensitive information.
  • Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks: Malicious actors can flood VoIP systems with traffic, causing service disruptions and rendering communication channels unusable.
  • Call tampering and manipulation: Hackers may alter VoIP call content, leading to misinformation, data tampering, or impersonation attempts.
  • Phishing attacks: Cybercriminals use social engineering techniques to trick users into revealing sensitive information, such as login credentials, by posing as legitimate VoIP service providers or technical support.
  • Vishing (Voice Phishing): Attackers use recorded voice messages or impersonate trusted entities to deceive users into divulging sensitive information over the phone.
  • Toll fraud: Criminals make unauthorized international or premium-rate calls, causing financial losses for the organization.
  • Malware and viruses: VoIP networks are susceptible to malware that exploit system vulnerabilities and compromise security.
  • Identity and spoofing attacks: Attackers can spoof caller ID information or impersonate legitimate users to gain unauthorized access to VoIP services.
  • Man-in-the-Middle (MitM) attacks: Hackers position themselves between two parties during a VoIP call, intercepting and potentially altering the communication without the users’ knowledge.
  • Insider threats: Employees or individuals with privileged access to VoIP systems may intentionally compromise security by leaking sensitive information or misconfiguring security settings.
  • Weak authentication: Inadequate authentication mechanisms can lead to unauthorized access, enabling attackers to use VoIP services maliciously.

How VoIP Encryption Works

VoIP encryption transforms the voice data into a secure and unreadable format during transmission, making it unintelligible to unauthorized parties.

One such method is the Secure Real-Time Transport Protocol (SRTTP) that provides confidentiality, integrity, and authentication for voice data. When a VoIP call is initiated, SRTP encrypts the audio packets using encryption algorithms like AES (Advanced Encryption Standard) before they are sent over the network.

Teams can also employ the following key systems:

  • Encryption Key Exchange: The VoIP devices exchange encryption keys on both ends before starting the call. These keys encrypt and decrypt the voice data during the call. This process ensures that both parties share a secret key securely, preventing unauthorized access to the encrypted communication.
  • Public Key Infrastructure (PKI): While similar to Encryption Key Exchange, PKI uses public and private key pairs, where the public key is used for encryption, and the private key is kept secret for decryption. This method ensures secure key distribution and management.

Another protocol for initiating and managing VoIP calls is Secure SIP (Session Initiation Protocol), which employs TLS (Transport Layer Security) to protect the signaling and call setup process.

Finally, you can use a VPN (Virtual Private Network) to encapsulate and encrypt voice data through a VPN tunnel.

Best Practices to Keep Your VoIP Secure

Cyber threats are often inevitable, but they don’t have to cost you everything. Consider the best practices for keeping your VoIP business system secure:

  • Implement strong authentication: Use strong passwords and multifactor authentication (MFA) to ensure only authorized users can access your VoIP system. 
  • Regularly update software: Keep all VoIP applications, firmware, and devices up-to-date with the latest security patches. Regular updates help address known vulnerabilities and strengthen system defenses.
  • Use encryption: Employ Secure Real-Time Transport Protocol (SRTP) to encrypt voice data during transmission.
  • Monitor network traffic: Utilize intrusion detection and prevention systems (IDPS) to monitor and detect suspicious activity on your VoIP network.
  • Segment your network: Separate your VoIP network from other data networks, creating dedicated VLANs (Virtual LANs) to reduce the risk of unauthorized access.
  • Install and configure firewalls: Control incoming and outgoing traffic, allowing only authorized VoIP traffic to pass through.
  • Train employees: Educate your employees about VoIP security best practices, such as identifying phishing attempts and protecting login credentials. Awareness training is crucial in preventing social engineering attacks.
  • Perform regular security audits: Conduct periodic security audits to assess the effectiveness of your VoIP security measures and identify weaknesses.
  • Implement regular data backups: Establish a disaster recovery plan. In case of a security breach or system failure, having reliable backups can help restore operations swiftly.

How to Choose a Secure VoIP Provider

With so many VoIP security providers available, how do you choose the right one? Use these tips to narrow your selection:

  • Look for providers that adhere to industry standards and possess certifications like ISO 27001 or SOC 2, indicating their commitment to security best practices.
  • Inquire about the provider’s network security measures, including firewalls, intrusion detection systems, and network segmentation to safeguard against cyber threats.
  • Review the provider’s privacy policy to understand how they handle user data. Ensure they have robust data protection policies and comply with relevant laws.
  • Verify that the provider offers various authentication methods, like MFA, to prevent unauthorized access to user accounts and administrative interfaces.
  • Evaluate the provider’s incident response capabilities and support services. Quick and efficient responses to security incidents are crucial in minimizing potential damage.
  • Check if the provider has redundancy measures and a disaster recovery plan to ensure service continuity during emergencies.
  • Review the SLAs to understand the provider’s commitment to service uptime, security, and resolution times for security-related incidents.
  • Choose a provider that openly communicates its security practices and regularly updates customers on security improvements and threats.

Most Secure VoIP Providers

While the specific rankings for the following VoIP security providers fluctuate, they are generally reliable. Review this table to select the appropriate security provider for you.

E2E EncryptionYesYesYesYesYesYes
Support HoursPhone: 24/7

Email: 24/7
Phone (M – F): 5:00 am to 6:00 pm

Chat: 24/7
Phone (M – S): 6:00 am to 6:00 pm

Chat: 24/7
Phone (M – F): 5:00 am to 6:00 pm

Chat: 24/7
Phone (M – F): 9:00 am to 6:00 pmPhone: 24/7

Chat: 24/7
HIPAA ComplianceYesYesYesYesYesYes
ISO Certification/SOC 2 ComplianceYesYesYesYesYesYes
Independent AuditsRegular, according to client needsAnnualAnnualRegular penetration testingIndependent security auditsAnnual

Frequently Asked Questions

Is landline more secure than VoIP?

Generally, landlines are more secure than VoIP because they are physically isolated, making them less susceptible to cyber threats. In addition, they don’t rely on Internet protocols for communication and can stay online even amidst Internet disruptions.

What attacks are VoIP most vulnerable to?

VoIP systems are most vulnerable to eavesdropping, call interception, DoS/DDoS attacks, call tampering/hijacking, phishing, fraud, and malware/viruses.

What encryption is used in VoIP?

Common forms of VoIP encryption include SRTP, TLS, and SIP over TLS. However, it is crucial to note that the overall security of a VoIP system also depends on other factors, such as proper implementation, network security measures, regular updates, and user awareness of safety best practices.


Even without anything to hide, watching your business data fall into the wrong hands (or ears, rather) can spell significant consequences. With the right VoIP security provider, you can keep your and your customers’ information safe and encrypted.

When shortlisting VoIP security providers, review their encryption methods, uptime, customer service availability, and additional features, should you need them. 

If you’re looking for a reliable and secure VoIP provider, your journey ends with ULTATEL. Our trusted cloud business phone system integrates with dozens of beloved CRM software and keeps your information safe.

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