VoIP Attacks: How Hackers Target Your Calls and How to Stop Them

When you make a call over VoIP, you're not just using the internet—you're exposing your phone system to VoIP attacks, malicious attempts to exploit vulnerabilities in internet-based phone systems. Also known as SIP hacking, these attacks can steal your calling credits, eavesdrop on conversations, or turn your system into a spam hotline. Unlike landlines, VoIP systems are connected to the internet, which means they’re visible to scanners, bots, and hackers looking for weak passwords, open ports, or outdated software.

One of the most common toll fraud, unauthorized use of a VoIP system to make expensive international calls happens when attackers guess default passwords on IP phones or PBX systems. They don’t need physical access—just an open SIP port and a weak PIN. Once inside, they can route hundreds of calls to high-cost destinations before you even notice. Another type of attack, called SIP flooding, overloading a VoIP server with fake registration requests to crash or disrupt service, can knock your entire phone system offline. And if your calls aren’t encrypted, someone on the same network can listen in using simple packet sniffers.

Good news: most of these attacks are preventable. You don’t need a cybersecurity degree. You just need to lock down your system. Turn off unused ports. Enforce strong passwords. Use SRTP encryption, secure media transport that scrambles voice data so it can’t be intercepted instead of outdated methods like SDES. Segment your VoIP traffic from your main network. Update firmware. These aren’t fancy tricks—they’re basic steps that 90% of businesses skip. And that’s why they get hit.

The posts below show you exactly how these attacks happen, what they look like in real systems, and how to fix them before they cost you money or reputation. You’ll find guides on securing SIP trunks, hardening IP phones, stopping toll fraud before it starts, and choosing the right encryption to keep your calls private. No theory. No fluff. Just what works.