What is Zero Trust Architecture?
Zero Trust Architecture (ZTA) is a cybersecurity model that operates on the principle of “never trust, always verify.” Unlike traditional network security approaches that assume everything inside the network perimeter is safe, Zero Trust treats every user, device, and connection as untrusted—whether it’s inside or outside the organisation’s network. By continuously verifying identity, device health, and access permissions, Zero Trust Architecture helps to prevent unauthorised access, contain potential breaches, and strengthen overall security posture in today’s increasingly remote and cloud-driven IT environments.
Zero Trust Architecture (ZTA) can play a vital role in helping businesses navigate both the PSTN switch-off and growing cybersecurity threats, especially as more organisations shift to digital, cloud-based communication systems such as VoIP and cloud telephony.
1. Secure Transition to Cloud Communications
As the PSTN is phased out, businesses must adopt internet-based solutions like VoIP and cloud calling. These technologies inherently increase exposure to cyber threats, especially when accessed remotely or via multiple devices. Zero Trust ensures that every connection request is authenticated, authorised, and continuously validated, reducing the risk of unauthorised access to these new communication platforms.
2. Protection of Distributed Networks
The move away from legacy phone systems often comes hand-in-hand with greater remote and hybrid working practices. Zero Trust Architecture helps protect users working from anywhere, ensuring they can securely access cloud telephony services and other business-critical systems without compromising network integrity.
3. Minimising Insider Threats and Lateral Movement
By enforcing least-privilege access and micro-segmentation, ZTA limits what users and devices can access, even once authenticated. This means that even if credentials are compromised during the PSTN transition (for example, via phishing or misconfigured systems), attackers can’t move freely through the network.
4. Improved Compliance and Audit Readiness
The Zero Trust model provides detailed visibility and logging of user activity, which is especially useful for demonstrating compliance with industry standards and data protection regulations (such as GDPR). As businesses modernise their communications, having this visibility helps maintain a strong security posture.
5. Future-Proofing Business Security
Moving from PSTN to cloud-based communication isn’t just a technical upgrade—it’s a strategic shift. Implementing Zero Trust ensures that your security model evolves in tandem with your infrastructure, preparing your business for future digital developments, whether that’s 5G, IoT, or AI-driven services.
What are the most common VoIP cybersecurity threats?
To be able to defend your business against cyberattacks, you need to know what you’re up against. Here are some of the most common VoIP security threats:
- Phishing attacks use social engineering techniques to trick your employees into clicking malicious links or downloading software that harvests confidential information, logins and passwords. A VoIP phishing attack, also known as ‘Vishing’, involves scammers using phone numbers similar to those of legitimate organisations. They leave a message about suspicious activity and when the victim responds, they are asked to verify their identity and disclose confidential information.
- Malware is usually a direct consequence of falling for a phishing attack. A malicious program or code can cause a wide range of system interruptions and errors. It can sabotage valuable information, shut down all your communication systems and even hold your business-critical data to ransom.
- Distributed Denial-of-Service (DDoS) attacks are designed to shut down an entire network. These attacks work by hackers sending your VoIP system high volumes of data, such as spam phone calls, which then trigger a wider system crash.
Call tampering is where hackers disrupt your live calls, reducing the audio quality, introducing long delays or creating total silence. This is done by preventing the delivery of your audio data packets or injecting noise packets into the communication stream. - Spamming over Internet Technology (SPIT) attacks is a component of some of the threats that we’ve already mentioned. SPIT attacks involve spammers sending audio messages to thousands of IP addresses in an effort to infect, overwhelm or phish for information.
- Man-in-the-Middle (MITM) attacks where an attacker intercepts message traffic and then pretends to be either the caller or the intended call recipient. Once an attacker has gained this position, they can record or modify calls to gain access to your confidential data.
How can I protect my business from VoIP-based attacks?
All those VoIP cybersecurity threats may seem daunting, but now you know what you’re up against, you can do something about it. Here are our top tips for keeping your VoIP system safe and secure:
- Educate your employees because they are usually your weakest link. You can have all the right safeguards in place, but it only takes one employee to click on a suspicious link or get fooled by a MITM attack.
- Disable any unnecessary features as they could create loopholes. If you’ve got the spec right on your VoIP system, you shouldn’t be paying for any unnecessary features. However, if you have, make sure you disable them to reduce the risk of attack.
- Update firmware and apps regularly to make sure everything in your business is running on the latest secure version.
- Use encryption so your data is protected even further. Even if it’s intercepted, encrypted data cannot be decoded and accessed by anyone other than the intended recipient.
- Test your VoIP network regularly to ensure it continues to stay safe against cyberthreats and hackers.
- Adopt a Zero Trust approach, which is a framework that assumes every component and connection is hostile by default. From there, only validated connections are then allowed. Zero Trust Architecture (ZTA) is the most effective way to ensure VoIP security. It’s worth taking a closer look at ZTA and asking your supplier about it.
Speak to our team of Cybersecurity experts to see how Zero Trust Architecture can support your business today!