Most Common VoIP Security Issues

Three lock icons, with the middle lock icon unlocked, to symbolize vulnerabilites and VoIP security issues.

When VoIP was first introduced to the world, the security concerns were minimal. In fact, there were very few concerns at all aside from reliability, cost, and functionality. As VoIP gains traction, like any new technology, more security issues arose.  Perhaps VoIP security issues are more noticeable considering VoIP is replacing the Plain Old Telephone System (POTS), which was the most secure communication system in the world.

If you’re currently researching VoIP systems or perhaps you’ve just had one installed, you might be wondering what the most common VoIP security threats are, so we’ve compiled a short list here today.

VoIP Security Issues


Sometimes called Vishing (for VoIP Phishing), this has been a problem all over the internet in recent years. Typically, cybercriminals will pose as email providers or banking institutions. After sending a simple SMS or email, they try to get the recipients to click on a particular link or phone a certain number. No one should reply to messages of this kind. Instead, if you have concerns, get in contact with the company these phishers are impersonating to see if there are any real issues you need to address.

Call Hijacking

Although this is a more sophisticated form of hacking, VoIP hackers are using it more and more, so it’s become a prevalent issue. Whenever a user makes a call on a WiFi hotspot, the hacker will attempt to hijack the call as well as steal sensitive information.

Call Tampering

This threat isn’t usually dangerous, but it does causes inconveniences. By injecting certain noise packets into the data stream, these hackers’ only motivation is to ruin the quality of your call. For some reason, this has become a threat despite it not providing any benefit or profit for the attacker.

Malware and Viruses

VoIP security issues can pop up when using software and softphones which are vulnerable, just like any other internet application, to worms, malware, and viruses. With the softphone applications running on PDAs, PCs, and other user systems, it creates an exposure to malicious code attacks in voice applications.

A mobile VoIP device glows with a blue lock icon, symbolizing VoIP security issues that could occur.

If you encounter any VoIP security issues, check this list to perform some preliminary troubleshooting, and then contact a VoIP tech support professional immediately.


A majority of hackers steal your personal information and credentials through what we call ‘eavesdropping.’ After a third-party gains access to your passwords, names, and phone numbers, they can effectively take control of the service. However, not all hackers steal credentials to make free calls.  Some hackers will eavesdrop it to obtain valuable information (such as business data or account passwords).

As a business, you don’t want your credentials going anywhere because it gives hackers the same access to your service as yourself. For example, they can make changes to the calling plans, extend credit, and access voicemail features.

Denial of Service

Often shortened to DoS, Denial of Service is where your network/device is attacked and blocked, denying you access to the system. When it comes to VoIP, the most common method of attack is to flood the service with SIP call-signaling messages, which drops all calls prematurely and halts any call processing. If you’re wondering why anyone would do this, it’s because the hacker would then have access to the VoIP system’s administrative facilities once call operation is no longer in process.

Man-in-the-Middle Attacks

If you are using an insecure WiFi connection, you are vulnerable to man-in-the-middle attacks. With an unsecured WiFi connection, the attacker will intercept a call and then reroute it through their own servers. If they’re successful, they can inject certain spyware and malware into the system of the hacking victim.

ID Spoofing

Nowadays, we can’t even trust caller ID as much as we once did. Some attackers can make calls under the guise of an entirely different caller ID. Of course, this is one of the few that could occur on traditional calls, so this isn’t exactly a new problem, but it does show you how careful we must be.

Audio Spam

Finally, this hacking method actually accounts for around 10% of all spam on the internet, making it the most common attack. Essentially, audio spam is the same as email spam but it’s instead of emails, it’s spam calls and voicemails. If you aren’t careful, audio spam can be just as dangerous.  Never respond to any of these suspicious calls or dial the number they provide.

For most people, they don’t experience any of these issues over the life of their VoIP system, but it’s always a good idea to be cognizant of these problems.  Let’s not forget; there are specialized hackers who wake up every morning with the aim of planting malware into VoIP systems. Therefore, it’s a good idea to have the number of your VoIP tech support professional on hand in case you suspect any issues. It’s also advisable to have regular checkups on your VoIP system so you can protect your phone, and so that you’re kept up-to-date with any VoIP security issues.

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