Is the Disturbing Colt Cyber Attack Incident the Real Reason Your Business Phones Are Suddenly Dead?

My Business Relies on a SIP Trunk; How Can I Build an Unbreakable Communication Plan After the Colt Incident?

Many businesses now use the internet for their phone calls. This is a common and often cost-effective choice. A company named Colt is a major provider of the technology that makes this possible. Recently, on approximately August 14, 2025, Colt experienced a significant cyber incident. This event has caused service disruptions for many of its customers, and the effects are spreading to other companies who rely on Colt’s services. If your business phones have stopped working, this incident could be the reason why.

This guide will explain what happened in simple terms. It will also help you understand if your business is affected and what steps you can take to protect your ability to communicate with customers and colleagues.

What is SIP Trunking and Why Does It Matter?

To understand the problem, you first need to know about the technology involved. Think of a traditional phone line as a physical copper wire running to your building. It does one job: carry phone calls.

Modern businesses often use something called SIP trunking. You can think of a SIP trunk as a virtual phone line. Instead of a physical wire just for phones, it uses your existing internet connection to make and receive calls. This technology is part of a broader category called Voice over Internet Protocol, or VoIP.

Companies choose SIP trunking for several good reasons:

• Cost: It is often cheaper than maintaining multiple traditional phone lines.
• Flexibility: You can easily add or remove lines as your business grows or your needs change.
• Features: It supports modern phone system features, like video conferencing and sending calls to mobile devices.

Colt is a company that provides these virtual phone lines to businesses worldwide. Other companies, which sell complete phone system solutions, also build their services on top of Colt’s network. One such example is Starface GmbH in Germany, which uses Colt for its Starface Connect service. The problem is that when a foundational provider like Colt has an issue, it creates a ripple effect.

The Details of the Cyber Incident at Colt

Around the middle of August 2025, Colt identified a cyber incident within its systems. According to their public statements, the issue was located in a business support system. It is important to note that Colt stated this system is separate from the main infrastructure that its customers use directly.

Upon discovering the incident, Colt took immediate and decisive action. To protect its customers and its own network, the company proactively disconnected the affected systems from its customer infrastructure. While this was a necessary safety measure to contain the problem, it had a significant consequence: services for many customers went offline. Businesses that rely on Colt for their phone systems found that their communications were suddenly cut off.

Colt’s investigation into the event is ongoing. The company has brought in external investigators and forensic experts to understand what happened. A key finding so far is that some data was stolen from their system. A top priority for Colt now is to figure out exactly what data was taken and to inform everyone who has been affected by this data theft. This process takes time, as investigators must be careful and thorough.

The Ripple Effect: How Starface Customers Were Impacted

The situation with Starface GmbH is a perfect example of how an issue at one company can affect many others. Starface provides cloud-based telephone systems to its own customers. To deliver its Starface Connect service, it relies on the SIP trunking technology provided by Colt. Starface is a customer of Colt.

When Colt took its systems offline as a precaution, the foundation of the Starface Connect service was temporarily removed. As a result, Starface customers experienced service problems. This is not because Starface itself was attacked, but because a critical supplier in its service chain was.

Starface has been communicating with its customers through a forum thread. They have relayed information from Colt, confirming that the attack was on Colt’s systems and that Colt’s actions were precautionary. This incident highlights a crucial concept in modern business: third-party risk. Your company’s security and operational continuity depend not only on your own safety measures but also on the security of your essential vendors and partners.

What This Incident Means for Your Business: An Action Plan

Whether you are a direct customer of Colt or use a service that might depend on them, this incident is a critical learning moment. Here are advisory steps you should consider to assess your situation and improve your business resilience.

Identify Your Dependencies

The first step is to find out if you are affected. Ask your IT department or service provider a direct question: “Does any part of our communication system rely on Colt’s network?” If you use a cloud phone system, ask the provider who their underlying network carrier is. Knowing who is in your “supply chain” is no longer optional.

Communicate Proactively

If you find that your services are affected, communication is key.

• Inform Your Team: Let your employees know what is happening, why the phones are down, and what the alternative communication methods are (e.g., mobile phones, email, messaging apps).
• Inform Your Customers: If phone support is a key part of your customer service, you need to let them know. Post a notice on your website, update your social media channels, and change your main phone greeting if possible to redirect them to other contact methods.

Review and Create Contingency Plans

This incident is a powerful reminder that any service can fail. Now is the time to ask hard questions about your backup plans.

• Do you have a backup phone service from a different provider?
• Can you quickly forward your main business number to a mobile number in an emergency?
• Does your team have a clear plan for what to do when a critical system like the phone network goes down?

This event at Colt demonstrates that even large, established providers are not immune to cyber threats. The lesson for every business is to prepare for disruptions. Your ability to continue operating during an outage depends on the plans you make before one ever happens. Resilience is built on preparation, not reaction.