How to Ensure Secure VoIP Communications

Voice over Internet Protocol (VoIP) phone systems have revolutionized business communications.

By sending voice data over the internet rather than traditional phone lines, VoIP allows for cheaper long distance and international calls, consolidated communication tools, and advanced features for employees.

However, with all these benefits come potential security risks that must be addressed.

In this post, we’ll break down the key steps you need to take to lock down VoIP and prevent eavesdropping, data theft, service interruptions, and other threats.

The VoIP Security Threat Landscape

Before diving into solutions, it’s important to understand the main risks facing VoIP networks today.

VoIP calls travel through the internet’s public infrastructure, which is inherently far less secure than the dedicated phone lines used by landlines. The packets of data in a VoIP call can be intercepted and monitored with the right tools.

VoIP is also vulnerable to:

Service interruptions: Hardware failures, power outages, network congestion, or cyber attacks can disrupt phone and video connections.
Malware infections: Viruses, spyware, and ransomware may be inserted into VoIP phones, networks, or programs
Denial-of-service (DoS) attacks: Overwhelming a VoIP system’s bandwidth capacity with junk traffic, rendering it unusable
Phone hijacking: Malicious actors taking control of VoIP phones to place unauthorized (and expensive) calls
IP PBX hacking: Criminals penetrating the PBX software to control an entire company’s phone system
Call fraud: Manipulating VoIP protocols to force unauthorized call routing and trigger service provider fees
Eavesdropping: Intercepting and recording private VoIP calls containing sensitive information
Data theft: Accessing voicemail boxes, contact lists, conferencing data, recordings, and other information stored in VoIP systems
Identity theft: Spoofing the caller ID to impersonate trusted individuals and gain access to privileged data

The main takeaway is that VoIP introduces new attack surfaces not present in landline systems.

But with proper precautions, the risk of a compromise can be drastically reduced. Now let’s explore the key steps for securing your VoIP deployment.

Physical Security Measures

A VoIP phone system relies on multiple hardware components working together smoothly. The servers, routers, IP phones, wiring, and other gear used for VoIP must be protected against unauthorized physical access, damage, and theft.

Start by storing all VoIP electronics in a locked server room or cabinet only accessible by authorized IT staff.

Network cables should be concealed within walls rather than exposed. Power supplies should be backed up by UPS battery units in case of electrical failure. Only devices specifically approved for network use should be able to connect over ethernet.

For additional hardware security:

Use managed PoE switches: Power over Ethernet (PoE) switches offer central control and monitoring capabilities. Disable any unrecognized or unapproved devices attempting to draw PoE power through the ethernet cables.
Install surveillance cameras: Monitoring who enters VoIP server rooms or tampers with devices can identify threats and help prosecute criminals.
Rack-mount gear: Securing routers, media gateways, and servers in locking server racks bolted to the floor protects against theft and accidental damage.
Login at the door: Require electronic keycard, biometric, or pin code access to server rooms housing VoIP infrastructure. Logs should show entry/exit timestamps for auditing.
Inspect wiring: Regularly check VoIP cabling for any signs of tampering, cuts, or taps that could indicate eavesdropping or hijacking attempts.

Physical security might not seem directly related to VoIP communications security, but it ensures unauthorized parties can’t directly access the core infrastructure. Criminals look for easy targets, so adding roadblocks like locks, cameras, and access controls makes you a much tougher prospect.

Locking Down VoIP Phones

The specialized desk phones and mobile softphones used in VoIP systems transmit all call media and data, so they need protections against tapping, malware, and misuse. Here are smart steps for securing VoIP endpoints:

Use encryption: Encrypt call audio, signaling data, and stored information to prevent interception. Use secure protocols like SRTP, TLS, and HTTPS wherever possible
Install signed firmware: Only install phone firmware from validated vendors so you know it’s legitimate. Disable TFTP or other methods that allow unsigned firmware downloads
Configure Wi-Fi securely: For wireless VoIP phones and softphones, ensure the Wi-Fi uses WPA2 or WPA3 encryption. Use VPNs when on public hotspots
Disable unnecessary features: Turn off unneeded settings that could expose vulnerabilities like excessive debug logs, remote management, provisioning modes, and unused network ports
Require PIN logins: Configure phones to require a user PIN before granting access to call logs and personal data. Auto-wipe data after repeated PIN failures
Monitor for anomalies: Track bandwidth usage, registrations, and calls to catch misuse and fraud. Automated tools can help flag anomalies 24/7
Keep updated: Vendors often release VoIP phone firmware patches to fix bugs and security holes. Apply all available updates promptly
Use Power over Ethernet (PoE): PoE ethernet cables transmitting both power and data prevent tampering with AC adapters on VoIP phones and other IP endpoints
Buy from major brands: Reputable phone makers like Yealink, Polycom, and Cisco tend to have better security than no-name brands. Research before purchasing

Your VoIP phones are critical endpoints secured access is key. But even if the infrastructure is buttoned up, employees can still introduce risks through their behavior.

Securing VoIP Softphones

VoIP softphones refer to software applications that allow users to make calls, hold video conferences, check voicemail, and access other voice services directly from their laptop or mobile device. While softphones provide greater flexibility than dedicated VoIP desk phones, they also introduce potential security risks.

Softphones essentially turn the user’s device into a phone accessible over the public internet.

Without proper safeguards, softphones could expose calls and internal networks to eavesdropping, malware attacks, fraud, and other threats.

Organizations should take measures to protect softphone communications and prevent unauthorized use. A VPN should be required when connecting softphones outside the corporate network to encrypt traffic over the public internet. Access credentials like usernames, passwords, or certificate files should be carefully managed to prevent misuse if compromised.

Remote device wipes can deactivate softphone apps if a device is lost or stolen. Monitoring tools can track softphone registration and usage patterns to catch anomalies.

Policies should clarify where and when staff can utilize softphones, and proper security training is essential.

Making softphone call encryption mandatory, restricting cut-and-paste or recording capabilities, and other policy settings tailored to the app help reduce improper usage. Signals intelligence solutions can automatically scan softphone call contents for signs of data loss, policy violations, or insider threats.

While softphones enable greater flexibility, they also require more vigilance compared to hard desk phones. Following security best practices tailored to softphones will help organizations harness their benefits while controlling associated risks.

With well-designed policies, monitoring, and training, softphones can be safely deployed to improve mobility and productivity.

VoIP Server Security Best Practices

The servers powering a business VoIP system serve critical functions like call routing, voicemail, auto attendants, meeting hosting, and more. Securing the server software and network protections is imperative to prevent threats like eavesdropping, fraud, DoS attacks, and service hijacking.

Follow these VoIP server security best practices:

Harden the OS: Use Linux or a secured Windows Server OS. Disable unneeded services, restrict root access, apply the latest patches, and configure a firewall
Encrypt the system drive: Encrypting all VoIP server data protects against breaches where someone gains physical access
Utilize VLANs: Segment VoIP servers and traffic into isolated virtual local area networks (VLANs). This contains threats and minimizes prying eyes
Install anti-virus: Scan regularly for malware, worms, spyware, and other threats that could be injected into the VoIP system
Enable QoS: Quality of service (QoS) settings prioritize VoIP traffic on your LAN to prevent call quality issues. This maintains uptime and reliability
Restrict remote access: Only allow remote administration access via VPN, disable RDP, and close unnecessary ports. Require strong passwords and two-factor authentication
Backup regularly: Schedule automatic backups of VoIP server data, configurations, and call recordings. Secure the backups offline to permit fast disaster recovery
Log and audit activity: VoIP systems should log all access attempts, calls, configuration changes, and events for fast issue identification and forensic evidence
Scan for vulnerabilities: Perform vulnerability assessments of all internal and external-facing system components to identify and patch weak points criminals could exploit

Securing VoIP servers ensures trustworthy system operations, maximum uptime, and defenses against data theft. But endpoints like IP phones have their own considerations, too.

VoIP Security Policies and Training

Your staff using VoIP phones, media gateways, softphones, and other tools are a primary source of potential security incidents through ignorance, negligence, or malicious intent. That’s why written security policies, training programs, and employee monitoring are so crucial.

Implement policies: Document appropriate VoIP use and handling in an employee policy manual. Prohibit recording calls without consent, unauthorized softphone installs, and similar behaviors.
Train new hires: Educate all employees with VoIP access on best practices for security, proper usage, device care, and reporting issues or suspicious activities.
Re-train annually: Require cybersecurity and VoIP policy refreshers every year or when new threats emerge. Keeping protocols top of mind improves compliance.
Lead by example: Managers should model ideal security behavior like using strong VoIP passwords, locking devices when away, and not discussing sensitive information on calls.
Report problems immediately: Employees should alert IT staff to any suspected VoIP issues like echoing, anomalies, or signs of tampering so they can be swiftly addressed.
Enforce with audits: Occasional user behavior audits help ensure protocols are being followed. Checks might include device inspection, policy quizzes, or call monitoring.
Limit call recording: Call recording features open the door for leaks of sensitive conversations. Only permit recording with a justified business need and make storage secure.
Beware social engineering: Train staff to recognize phishing attempts, unknown callers demanding information, or other social engineering threats targeting your VoIP network.
Verify identities: Before disclosing confidential data or initiating financial transactions, employees should confirm a caller’s identity through a secondary means like returning their call through the company directory.
Deploy speech analytics: AI-powered speech analytics can automatically detect speech patterns that indicate policy violations, data exfiltration, fraud, confidentiality breaches, and insider threats over company calls.
Monitor usage: Techniques like capturing IP phone screen displays or recording video of public spaces can help identify unauthorized or improper VoIP usage and discourage it.
Enforce separation: Ensure employees only have access to the specific VoIP features and data they need for their job through internal segmentation and access controls.
Address issues: Consistently enforce VoIP policies through reprimands and additional training. Promptly revoke system access for repeat or intentional violators.

Your employees shouldn’t see security rules as obstacles, but as protecting them and the business from harm. With the right workplace culture that prioritizes collaboration and transparency around VoIP security, most will happily cooperate.

Layered Defenses for Maximum Protection

No single security precaution can fully protect a VoIP phone system and communications. That’s why your strategy should incorporate layered defenses spanning tools, policies, training, and vigilance.

Here are some additional layers to consider:

Session border controllers (SBCs): SBCs bolster call quality while also providing security features like encryption, DoS prevention, and fraud detection.
Intrusion detection and prevention systems (IDS/IPS): IDS and IPS appliances identify and block VoIP threats like SIP floods, spoofed callers, fuzzy war dialing tools, and other attack traffic.
Next-gen firewalls: Firewalls with deep packet inspection defend VoIP servers from unauthorized access attempts, abnormal behavior, known threats, and more.
Web content filtering: Block access to websites distributing VoIP malware, hacking tools, stolen data, and other sources of potential compromise across the company network.
Access control lists (ACLs): ACLs enforce which devices or users can access certain parts of a VoIP system. This limits damage if credentials are compromised.
Data loss prevention (DLP): DLP tools detect potential confidentiality breaches across calls, video chats, voicemails, recordings, and other VoIP data interactions.
Bring your own device (BYOD) controls: Mobile device management, containerization, and other BYOD systems ensure personal phones used for business VoIP softphones still maintain security.

Proactive monitoring, anomaly detection, penetration testing, and staying up-to-date on the latest VoIP threats can provide additional insight and protection from emerging risks. Never get complacent about VoIP security!

Choose a Secure VoIP Provider

While this post has focused on securing your own VoIP implementation, provider choice plays a major role as well. Even if your internal systems are locked down, a vulnerable service provider could still be compromised and expose your calls and data.

Here are key criteria to look for in a secure VoIP vendor:

End-to-end call encryption
Hardened data centers with SSAE 18, SOC 2, or ISO 27001 certifications
Regular third-party penetration testing and vulnerability assessments
Minimal data retention for only what’s absolutely required
Strong customer authentication and access controls
DDoS mitigation and geo-redundant infrastructure
Disaster recovery provisions like failover data centers
Up-to-date security features and protocols
Responsible disclosure for handling vulnerabilities
Notable security partners or advisory firms

Leading business VoIP providers like Nextiva, Zoom, and RingCentral tick many of these boxes while also delivering excellent call quality, management features, global coverage, and great support.

Do your due diligence to pick a vendor that aligns with your security standards.

Maintain Vigilance for Ongoing VoIP Protection

Securing VoIP communications takes continued effort in the face of evolving threats and new attack techniques. While total security is impossible to guarantee, taking the right steps makes the likelihood of a damaging VoIP breach extremely low.

With planning and care, you can harness VoIP’s awesome advantages while also keeping your business calls secure.

To explore affordable VoIP solutions that include leading security protections right out of the box, check out our favorite VoIP phone services—there, you’ll learn about our top picks, customer support, features, pricing, and more.