Complete Guide to VoIP Security, Encryption & Vulnerabilities

VoIP phone systems optimize available agents, streamline complicated business processes, and dramatically improve the customer experience.

But is VoIP secure? What steps should you take to reduce the risk of data leaks, hacks, and other security threats? What are your business's biggest security risks--and how is your VoIP provider protecting you against them?

Read on to learn about the most common VoIP security issues and how to guard against them, the role of data encryption, and the right questions to ask your business phone system provider. Though no one can eliminate cybercrime, the information in this post can significantly lower your business's risk of being attacked.

2026 VoIP Security Updates: A Summary

Below, we’ve listed the most important VoIP security information you need to know to protect your business, employees, and customers in 2026:

• Increased data breaches: In the Identity Theft Resource Center’s 2025 half-year report, the number of people affected by data breaches was already over half that of 2024 with 165.7 million data records being exposed.\[*]
• Rise in ransomware: Ransomware continues to be a large security risks, making up about 44% of breaches in 2025 which is up from 32% of breaches in 2024.[*]
• Data stored across locations is more vulnerable: 61% of organizations store sensitive information in multiple locations.[*] Nearly 40% of all data breaches attack multiple data storage environments/devices.[*] The costs of multiple environment data breaches are the most expensive–over 17% higher than private cloud data breaches
• AI-powered cyber attacks: 74% of security leaders believe AI-powered cyber threats are a significant hurdle today.[*] Hackers are exploiting AI to automate large-scale cyber attacks, create malware and malicious QR codes, and make phishing scams more sophisticated
• Hacking IoT devices: IoT devices (fitness wearables, smart home/office devices, patient medical devices, etc.) and industrial IoT devices (sensors, GPS trackers, barcode scanners) are popular cybercrime targets in 2026. One 2025 study estimated that there are 820,000 IoT hacking attempts per day.[*]
• Remote work increases security risks: Offsite/BYOD devices used by remote team members are difficult to properly secure, a vulnerability hackers will likely exploit in 2026. A survey revealed that within 2 months of switching to remote work, 46% of businesses experienced at least one cyber security scare.
• Third-party software increases exposure to hackers: Supply chain and third-party vendors saw an increase in the percentage of overall breaches from about 33% in 2024 to 44% in 2025, reflecting the overall growth in usage of cloud-based services.[*]
• Small businesses are primary targets: Cyber attacks on small businesses are up 16% with about 75% of small businesses experiencing at least one attack in 2025.[*] 
• Consumers prioritize cybersecurity: 76% of consumers don’t shop with businesses they don’t trust to protect their personal data, and transparency regarding how companies will use/share their personal data is the top consumer privacy concern.[*]
• Privacy violations have devastating financial consequences: The average cost of a data breach was $4.44 million in 2025 – a decrease from 2024 which saw an all time high of $4.88 million in losses.[*] In addition to legal fees/damages, the hidden costs of data hacks include lost work time, lost customers, and network downtime

Is VoIP Secure?

Yes, VoIP is secure when calls are encrypted with TLS and SRTP, accounts are protected by strong authentication, and you buy from a provider that publishes its certifications and audit results.

VoIP security is the set of protocols, policies, and controls that protect internet-based calling, from the encryption applied to voice packets in transit to the password, access, and network rules that keep attackers out of your phone system.

What is VoIP Encryption?

VoIP encryption is the data security process of scrambling voice data packets into unreadable jumbles while they are in transit, preventing them from being intercepted or deciphered by hackers.

Even if a hacker intercepts the call, encryption ensures they won’t be able to make sense of anything they discover.

To understand how encryption works, we need to take a closer look at the transmission process.

Data Transmission and SRTP

When voice data packets are transferred from the sender to the recipient, they use an IP transport protocol called the SRTP (Secure Real-Time Transport Protocol.) SRTP is a cryptographic protocol that applies the Advanced Encryption Standard (AES) to data packets, authenticates messages, and offers additional protection against data breaches and cyber attacks.

In addition to SRTP, VoIP providers use Transport Layer Security (TLS), or SIP over TLS, to encrypt and protect additional call data. TLS scrambles data like caller names/phone numbers, prevents message tampering, and stops call eavesdropping.

Quality VoIP providers should offer both TLS and AES Encryption.

What is End-To-End Encryption? 

End-to-end encryption (E2EE) is a cyber security call that directly encrypts communication data between endpoints, preventing third parties from accessing call/message data while it moves from sender to recipient (and vice versa.)

Standard TLS encryption includes only client-to-server encryption (C2S), meaning hackers could still access all network data, eavesdrop on and record calls, manipulate files during transfers, and review all business message history.

E2EE uses encryption and decryption keys to protect data at rest and in transit, preventing hackers and telecom providers from accessing your data.

Always ensure end-to-end encryption is enabled before using your VoIP system, as end-to-end encryption is not always the default option.

VoIP vs. Landline Security: Which Is Safer?

People switching from analog lines may assume copper is inherently safer, but a landline call travels unencrypted by design. Anyone with physical access to the line or the junction box can listen in without leaving a trace. VoIP moves risk from the physical layer to the network layer, where encryption and monitoring can address it.

A properly configured VoIP system is the more defensible of the two. Landlines have fewer attack surfaces but almost no defenses. VoIP adds encryption, authentication, and audit trails for detecting and stopping attacks that could otherwise go unnoticed.

Types of VoIP Security Risks and How to Prevent Them

While it’s impossible to prevent 100% of security and privacy attacks, taking a proactive approach to VoIP security drastically reduces their numbers and the scope of their impact.

Below are the most common VoIP security risks, plus actionable tips on how to prevent them.

Packet Sniffing

What It Is

Packet sniffing is a common VoIP software attack where hackers interrupt the voice data packet transit process to steal and log unencrypted information. Packet sniffers take control of your router and drop packets into data streams via a black hole attack, resulting in slowed network service or a complete loss of network connection. This lets packet sniffers steal usernames, passwords, and other sensitive data.

How To Prevent It

Prevent packet sniffing by:

• Using a reliable VoIP VPN
• Turning on end-to-end encryption
• Enabling 24/7 network monitoring with real-time alerts for suspicious login attempts, unfamiliar devices, etc.

DDoS Attack

What It Is

A DDoS (Distributed Denial of Service) attack is caused by a network of hacker-controlled botnets that intentionally overwhelm networks, websites, and servers to prevent businesses from accessing their own VoIP services.

Common signs of a DDoS attack include:

• Unusual and prolonged bandwidth spikes
• 503 HTTP Error Responses
• Slowed service
• A sudden surge in traffic from similar devices, IP addresses, or locations

How To Prevent It

To mitigate DDoS attacks:

• Use a dedicated VoIP Internet connection for VoIP, like VLANs (Virtual Local Area Networks) specifically provisioned for VoIP traffic
• Use managed encryption if sharing across a wide area network (WAN)

Ransomware

What It Is

Ransomware is a type of malware that mimics a secure email file attachment to encourage users to open or download the file on their device. Once downloaded, the ransomware encrypts server files so the original file owner cannot open then unless they make a ransom payment. These payments are often collected through digital currencies like Bitcoin.

How To Prevent It

To prevent ransomware attacks:

• Switch to a zero-trust data architecture
• Backup files on a separate drive/device to avoid having to pay the ransom
• Install anti-virus and anti-malware programs, use firewalls with application control
• Block malicious IP addresses or IP addresses from certain countries (geo-filtering)
• Enable 24/7 network monitoring

Vishing

What It Is

Vishing is s VoIP-based phishing attack where a hacker calls a business pretending to be from a trusted phone number or source, then encourages callers to reveal sensitive information like passwords, credit card numbers, and more.

Caller ID spoofing displays seemingly legitimate information to intentionally confuse victims. For example, a hacker may appear to be calling from your bank’s phone number. They’ll often claim your account has been compromised, scare you, then request your password to “secure your account.” It’s a lower-tech, but incredibly effective, VoIP security threat.

Signs of a vishing attack include:

• Extreme urgency/pushiness from the caller
• A caller that provides sensitive information, then asks you to verify/update it
• Unexpected calls from known numbers or well-established companies
• Short and unusual phone numbers on call screening Caller ID display

How To Prevent It

To prevent vishing, targeted agencies should:

• Avoid providing information over the phone to anyone claiming to be the IRS, Medicare, or Social Security Administration (they do not initiate contact)

• Verify all phone requests, even familiar ones
• Train agents to refuse to disclose sensitive information unless cleared by a supervisor
• Join the Do Not Call Registry
• Don’t respond to unfamiliar automated voice prompts

Malware and Viruses

What It Is

Malware and viruses consume network bandwidth, add to signal congestion, cause VoIP call signal breakdowns, and open businesses up to major security issues. Viruses and malware also corrupt data being transmitted across your network to cause packet loss.

hey also contribute to future vulnerabilities by creating Trojan backdoors, which future hackers exploit to call tamper or steal information relayed in your calls.

How To Prevent It

To prevent malware and viruses:

• Enable E2EE encryption
• Regularly check for network infection
• Purchase routes that actively block malware and dangerous sites from your network
• Implement VoIP-compatible firewalls to scan data for security issues

Phreaking Attack

What It Is

A phreaking attack is a type of fraud where hackers break into a VoIP system to make long-distance calls, change calling plans, add more account credits, and make any additional phone calls they want.

Hackers can also steal stored billing information, access voicemail, and reconfigure call forwarding and routing strategies. Hackers call your phone system and enter a PIN Number to access an outside line, which allows them to make calls and charge them to you.

A sudden increase in phone bills, excessive unknown numbers in call logs, or calls made during off-hours, all indicate a possible phreaking attack.

How To Prevent It

Prevent phreaking by:

• Encrypting all SIP trunks
• Changing account passwords frequently
• Purchasing ransomware protection software
• Avoiding autosaving billing information

SPIT

What It Is

SPIT, or Spam over IP Telephony, is similar to phishing attempts and email spam. SPIT sends prerecorded messages to VoIP Phone numbers, intentionally overwhelming them to deny service and carrying viruses/malware.

How To Prevent It

• Use a firewall to identify and control spam
• Only use a reputable VoIP provider

Man-in-the-Middle Attacks

What It Is

A man-in-the-middle attack is a difficult-to-detect cyber attack where a hacker inserts themselves between a VoIP network and the call’s intended destination.

This usually happens on public and unsecured WiFi networks, as hackers can easily intercept the call, reroute it through their own servers, and infect it with spyware, malware, and viruses.

How To Prevent It

Prevent man-in-the-middle attacks by:

• Avoiding public WiFi
• WAP/WEP encrypting access points
• Improving router login credentials
• Using a VPN

Toll Fraud

What It Is

Toll Fraud is when hackers intentionally make an excessive number of international calls from your business phone system to get a portion of the revenue the calls generate for themselves.

Sometimes known as International Revenue Sharing Fraud (IRSF), toll fraud works when international premium rate number (IPRN) providers buy and resell phone numbers from carrier groups or country regulators. Hackers then generate a high number of international calls through those numbers, taking their cut through the IPRN.

How To Prevent It

To prevent toll fraud:

• Enable two-factor authentication on your accounts
• Restrict geo-permissions by only allowing users to contact certain countries
• Set rate limits on concurrent calls and call durations

Call Tampering

What It Is

Call tampering is when a hacker injects additional noise packets into the call stream, instantly destroying the call quality and forcing both parties to hang up. These hackers can also prevent packets from being delivered to their proper destination, which makes for spotty, garbled service and long periods of silence.

How To Prevent It

To prevent call tampering:

• Enable end-to-end encryption
• Use TLS to authenticate data packets
• Ese endpoint detection software

VOMIT 

What It Is

Voice over Misconfigured Internet Telephones, or VOMIT, is a VoIP hacking tool that converts conversations into files that can be played anywhere, making it easy to siphon information from your business phone system.

This type of eavesdropping helps attackers gather business data like call origin, passwords, usernames, phone numbers, and bank information.

How To Prevent It

To prevent VOMIT:

• Use a cloud-based VoIP provider that encrypts calls before they are sent
• Work with HIPAA and HITECH-compliant providers only
• Create a private PBX network, not a public one

Voicemail Hacking

What It Is

Voicemail hacking happens when an attacker guesses or brute-forces the PIN on a voicemail box, usually by working through default codes and simple sequences. Once inside, they can change the outgoing greeting so the mailbox accepts collect charges, listen to messages containing account numbers and internal details, and reroute call forwarding rules to premium international numbers that bill back to your account.

How To Prevent It

To prevent voicemail hacking:

• Change every default voicemail PIN before handing a phone or extension to an employee
• Ban sequential and repeating PINs (1234, 0000, 1111) in your password policy
• Disable international call forwarding from the voicemail menu
• Review call logs monthly for unfamiliar international numbers and off-hours activity
• Lock out voicemail boxes after a set number of failed PIN attempts

Compromised Credentials and Unauthorized Access

What It Is

Stolen credentials let attackers enter a phone system as legitimate users. Attackers obtain or test credentials through phishing, passwords exposed in unrelated breaches and reused across accounts, or automated SIP brute-force and credential-stuffing attacks against admin portals and individual extensions. Once logged in, an attacker can place calls, pull call recordings, change routing, and add extensions without triggering an alarm.

Warning signs of compromised credentials include:

• Higher-than-normal call volume or minutes on a single extension
• Unknown numbers appearing in call history
• Calls placed well outside business hours
• New extensions, users, or forwarding rules nobody on your team created
• Repeated failed login attempts against the admin portal

How To Prevent It

To prevent unauthorized access:

• Require multi-factor authentication on every VoIP account, starting with admin logins
• Avoid email addresses as usernames, because they are already public and give credential-stuffing attacks a known username
• Revoke accounts and SIP credentials immediately when an employee is offboarded
• Set lockout thresholds so accounts freeze after a handful of failed attempts
• Limit admin privileges to the smallest group that needs them

VoIP Security Best Practices

VoIP security best practices for IT leaders, businesses, and employees include:

• Implement a strong password policy: Prevent brute force attacks by developing a consistent password policy that prevents employees from using the same password for multiple accounts, bans the use of personal details in passwords (house/phone number, family names, etc.), and requires a new password at least every two weeks
• Avoid public WiFi: Since malware and other viruses are easily spread over an unsecured 802.11x wireless network, instruct team members to avoid using public/unsecured WiFi to access their VoIP phone system
• Conduct routine security audits: Security assessments should be performed by independent and verified security agencies. They should include patching procedures, gateway assessments, firewall configuration, cyberattack simulations, and application-based security scanning
• Consistently update software: Enable automatic updates to access security and feature upgrades, fix packet loss, and patch VoIP phones
• Protect BYOD/mobile devices: Enable end-to-end encryption on all work-related devices, use a session border controller to connect remote employees to SIP trunks and analyze all VoIP traffic
• Segment voice traffic onto dedicated VLANs: Keeping phones and softphones on their own VLAN means a compromised laptop, printer, or IoT device on the data network has no direct path to your call traffic or phone system management interfaces
• Deploy a firewall with intrusion detection/prevention: Tune rules to the SIP and RTP ports your system actually uses, close everything else, and configure the IDS/IPS to flag and block IP addresses generating registration floods or repeated failed authentication attempts
• Put a session border controller at the network edge: An SBC filters inbound signaling, absorbs denial-of-service floods before they reach your PBX, hides internal topology, and enforces secure call routing and codec policies

How to Tell If Your VoIP Provider is Secure

The below list of questions will help you to determine the strategies and levels of security a cloud communications system has in place:

• What is the guaranteed uptime? VoIP providers should offer a guaranteed minimum 99.9% uptime, a real-time network status page, and should have multiple global points of presence
• What is the incident response time? Ask how long it takes for a VoIP provider to both respond to a security incident, notify all users, and restore service. Understand the protocols in place, your account’s priority level, and how specific cyber attacks are “scored” (Level 1, Level 2, etc.)
• What preventative security measures are in place? Is 24/7/365 network monitoring standard? Is end-to-end encryption available, and is it the default option? What physical security measures are in place? How often is data backed up? Are updates automatic or manual? What antivirus software is used?
• What security certifications does the provider have? Essential security standards and certifications include SOC 2 Type 2 (Service Organization Compliance), PCI Compliance (Payment Card Industry), HIPAA compliance, ISO/IEC 20071 certification, etc.
• What third-party applications does the provider software use? What is the user data sharing agreement, and how does the provider ensure third-party platforms meeting security requirements?

Compliance Requirements for Regulated Industries

Certifications on a provider’s website prove only the provider’s side of the arrangement. Compliance also depends on how you configure the phone system, which features you disable, and what you document. The requirements differ by framework:

• HIPAA: Covered entities and their business associates need a signed Business Associate Agreement from the provider before any protected health information touches the platform. For the phone system, that usually means turning off voicemail-to-email and voicemail transcription (or routing them only through the provider’s encrypted portal), restricting call recording storage and retention, limiting which staff can access recordings and transcripts, and logging every access to patient communications.
• PCI DSS: If agents take card numbers over the phone, card data must never sit in a recording or a transcript. Use pause-and-resume or automatic recording suppression during payment capture, or hand the caller to a secure IVR payment flow. PCI also expects card-handling systems to be segmented from the rest of the network. Use a dedicated voice VLAN, conduct regular penetration testing, and document access controls for anyone who can retrieve recordings.
• Data residency: GDPR and similar regimes require call data, recordings, and metadata for certain customers to stay on servers inside a specified country or region. Ask the provider which data centers serve your account, whether you can pin storage to a chosen region, and where support staff access data from. Configure retention so recordings are purged on the schedule your policy requires.
• Documentation: Keep your BAA, data processing agreement, provider audit reports, and a record of your own configuration decisions as proof for auditors.

The Most Secure & Encrypted VoIP Providers  

When it comes to security, and especially encryption, not all VoIP providers are created equal.

Providers offering encryption and superior security features are outlined in the table below.

FAQs

Below, we’ve answered some of the most common VoIP security questions.