Blog

VoIP Security

VoIP phone systems are extremely secure as long as your business implements and maintains it properly.

This involves acquiring your system from a certified provider, training your staff against social engineering attacks, and setting up your network infrastructure, access and monitoring appropriately.

This article covers the principal security threats against VoIP phone systems, gives best practices on how to avoid them and what to do when things do go wrong.

Contents

Why is VoIP security important?
VoIP security checklist
VoIP security threats
Best practices for VoIP security
VoIP security compliance

VoIP provider security checklist

The simplest way to have a secure VoIP phone system is by choosing a reputable, compliant provider with a proven track record who will help protect your system against potential threats.

Use this checklist to confirm your provider meets essential security standards:

Encryption protocols: TLS and SRTP for call and data security.
Fraud detection: Robust systems to identify and block suspicious activity.
Compliance certifications: GDPR, ISO 27001, and other relevant standards.
Regular updates: Frequent security patches and system improvements.
Data centre security: Advanced measures to safeguard stored information.
Training: Offer regular VoIP cybersecurity training for employees.

VoIP security threats

VoIP systems from reputable providers offer robust defences, including encryption, built-in security features, and proper network integration.

However, no cybersecurity system is immune to human error. Social engineering threats exploit employee naivety, and some businesses will undoubtedly cut corners and opt for cheaper VoIP, lacking appropriate defences (See our article on VoIP costs for business).

Here, we explore the key cybersecurity threats that apply to VoIP systems:

Vishing (VoIP Phishing)

Purpose: To steal sensitive information, such as login credentials or financial details.
Who is vulnerable? Employees lack training in social engineering awareness.

Vishing manipulates people, not systems. Attackers impersonate trusted entities, such as IT staff, and use spoofed caller IDs to deceive employees. AI-driven tactics, like voice cloning, have made these attempts more convincing.

Training employees to verify caller identities, use advanced voice authentication, and avoid sharing sensitive information can stop these attacks.

VoIP fraud

Purpose: Financial exploitation via unauthorised premium-rate calls.
Who is vulnerable? Businesses with weak authentication protocols or exposed systems.

Hackers gain access by brute-forcing passwords, exploiting vulnerabilities, or vishing. They rack up charges on premium or international calls, leaving them with inflated bills. Businesses can combat fraud by implementing strong password policies, multi-factor authentication, and fraud detection systems from their VoIP provider.

DDoS attacks

Purpose: Disrupt business operations or extort companies.
Who is vulnerable? Businesses with poorly secured VoIP servers.

Distributed Denial of Service (DDoS) involves flooding a VoIP server with excessive traffic, overwhelming its resources and causing it to crash. Hackers often use botnets (i.e. networks of infected devices) to direct the attack, making it difficult to trace. Businesses can mitigate this risk by using firewalls, load balancers, and cybersecurity software to detect and block malicious traffic.

UCaaS and IoT attacks

Purpose: Gain broader system access via weak IoT devices or UCaaS platforms.
Who is vulnerable? Businesses using outdated or poorly configured systems.

UCaaS integrates multiple tools, such as project management and CRM software with VoIP. IoT devices, like smart conference systems, can also expose VoIP networks if not secured. Strong passwords, encryption, network segmentation and implementing these through a trusted provider help protect against such exploits.

Call tampering

Purpose: To disrupt communications or harm business credibility.
Who is vulnerable? VoIP systems without encryption protocols or poor network security.

Call tampering manipulates VoIP data, causing dropped or low quality VoIP calls or altered audio. While rare in secure systems, experts speculate that AI may enable attackers to intercept data before or after encryption, so its worth keeping an eye out.

VOMIT (Voice Over Misconfigured Internet Telephones)

Purpose: Extracting call data or metadata for espionage.
Who is vulnerable? Businesses with misconfigured VoIP systems.

VOMIT exploits unsecured VoIP setups, though modern systems with encryption make this less common. However, AI is driving new methods to bypass protections. Regular VoIP audits and proper system configuration are standard ways of preventing VOMIT.

Best practices for VoIP security

The best practice is to lean on a trusted VoIP provider to ensure your system and network are appropriately secure. See our VoIP provider checklist to ensure your chosen provider meets security standards.

Even with a reliable provider, it is important to understand these best practices to ensure they are implemented.

Employee training

Phishing and social engineering attacks are among the most common threats. As VoIP is inherently a communication tool, it’s especially vulnerable to human error. Ensure your employees know how to recognise phishing attempts and follow security protocols to reduce risks.

Threat detection and monitoring

Ensure network monitoring for signs of suspicious activity, such as sudden spikes in VoIP usage, unexpected call logs, or redirected searches is taking place. Implement an Incidence Response Plan to respond quickly to breaches.

Secure your Network

Ensure your VoIP system is securely integrated into your business network. Place it behind a corporate firewall and use segmentation methods like SD-WAN or SASE to limit the impact of a potential breach. Physical segmentation through network switches adds an extra layer of security.

Secure Access

Control access to your VoIP system with robust measures like enforcing multi-factor authentication (MFA), strong passwords, VPNs for remote access.

Access to your VoIP system needs to be well-designed. All employees should use multi-factor authentication, strong passwords, and VPNs for remote logins. For maximum security, adopt Zero Trust Network Access to ensure only authorised users and devices can connect, even when personal devices are in use.

VoIP security compliance

Cybersecurity compliance of VoIP phone systems is critical for all parties involved. In other words, for your cloud-based VoIP provider hosting the service and your business as a user of this service. Here is how it applies to each:

Your business’s compliance

Your VoIP system must adhere to the same cybersecurity standards as the rest of your network.

For critical industries like finance, healthcare, or retail, securing sensitive data to very high standards isn’t optional but a legal requirement to avoid fines and protect customers.

Regulations like the DPA 2018 (customer data protection), PCI DSS (card payment security) and HIPAA (patient information security) all apply to VoIP as this information is commonly handled over voice or any other comms integrated with the system.

Non-compliance results in fines, lawsuits, and reputational damage.

Your VoIP provider’s compliance

Choosing a compliant VoIP provider is essential to mitigate risks. Reputable providers adhere to strict standards, offering encryption, secure data storage, and regular updates.

Here are the key VoIP provider accreditations:

ISO 27001 (information security management).
Cyber Essentials Plus (UK government-backed cybersecurity certification).
STIR/SHAKEN (prevents caller ID spoofing).
PCI DSS (if handling payment data).
ISO 27701 (privacy information management).
SOC 2 (focus on security, availability, and confidentiality).

Read our guide on understanding business VoIP.

What to do if I get hacked through my VoIP?

A quick and effective VoIP incidence response plan is key to survive a cybersecurity breach, minimise damage and prevent future incidents. Even small business VoIP systems should have one.

Follow these steps to stay in control:

Isolate affected systems: Immediately disconnect compromised VoIP systems from the network to contain the breach.
Notify your provider: Contact your VoIP provider for support in mitigating the issue and restoring secure operations.
Inform stakeholders: Notify internal teams, clients, and regulators as required by law, such as UK GDPR reporting standards.
Investigate and analyse: Conduct a post-incident review to identify the breach’s cause and improve defences.