VoIP Security Threats & How to Be Prepared

Computers, smartphones and tablets aren’t the only tech devices susceptible to security threats and incidents. VoIP systems share the same digital pathways as computers and mobile devices, making them just as vulnerable to security issues as the laptop sitting on your desk right now.

Fortunately, modern VoIP systems are equipped with the tools business owners and VoIP administrators need to protect organizations from security breaches and deflect most issues before they happen. Let’s take a look at some of the most common VoIP security threats and how to prevent them.

Call Hijacking

Session Initiation Protocol (SIP) is the method VoIP systems use to initialize and terminate calls between people. Vulnerabilities in the protocol open the door for hackers to exploit weaknesses in the system and hijack in-progress calls by quietly transferring them elsewhere. VoIP call encryption is key to preventing hijacks by obscuring call-specific information hackers need in order to intercept it.

DOS Attacks

Denial of Service (DOS) attacks occur when hackers flood a VoIP server with inauthentic data packets in order to slow down or stop system traffic. At best, DOS attacks are a temporary annoyance. At worst, they can disrupt your business for days and cost you thousands of dollars in lost sales and productivity. Regular network security audits can help IT teams spot and address vulnerabilities in your VoIP system before they expose you to DOS attacks.


Unauthorized interception of audio streams is one of the most common threats in a VoIP environment. Packet capture tools allow anyone to tap into and listen in on unencrypted VoIP traffic to hear conversations traveling across the network. VoIP systems that use Secure Real-time Transport Protocol (SRTP) shield audio traffic with enhanced security features like replay protection, message authentication and data encryption keys.

ID Spoofing 

Caller ID spoofing is easier over VoIP than traditional telephone systems because an attacker only needs access to the system’s gateway server or configuration settings. Once they gain access, they can easily change the number that displays on a call recipient’s phone to anything they wish. To protect systems from ID spoofing, administrators should make sure all VoIP infrastructure security features for servers, devices and networks are scanned, updated, patched as needed and monitored for suspicious activity. Admin access authentication mechanisms like Secure Shell (SSH) for remote system management are strongly recommended as a front-line deterrent to hackers and encourage them to move on in search of less secure systems.


This type of security threat, also known as vishing, is a voice-based variant of the notable email scheme data thieves use to obtain personal information from their victims. Attackers use ID spoofing to trick call recipients into believing they’re communicating with their bank, Paypal, Amazon or another legitimate business. Victims are enticed to give up sensitive personal data when asked to confirm details of their account. Phishing is difficult to prevent since it targets the end user rather than the VoIP system itself. Admins should remain vigilant for suspicious network traffic and educate end users about the dangers of phishing schemes.

VoIP systems are a great way for companies to save money, increase productivity through easier workplace collaboration and stay competitive in global markets. Any technology that is based on or uses the Internet is vulnerable to security breaches and attacks. Threat awareness is key to determining what your company should keep in mind when choosing and deploying VoIP systems.

By: Lisa McGreevy

Bio: Lisa Hoover McGreevy is a professional freelance journalist and blogger with more than 15 years experience covering enterprise products and services, brand marketing, and emerging technology. Lisa is based in Tampa, FL. Contact her at [email protected]

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