The breach was first noticed on 12 August 2025, when the company detected problems with an internal system.
In a blog post, the company, which connects 900 data centres across Europe, Asia and North America, confirmed the attack but stressed the affected system was separate from customer infrastructure.
The stolen files include a million documents with employee salary data, financial information, customer contracts, personal details of executives and staff, network designs and software development files.
“We’re really sorry that some of our support systems, including Colt Online and our Voice API platform, continue to be unavailable,” the company said in a statement.
“As a precaution following a cyber incident affecting our internal systems earlier this week, we’ve temporarily taken these services offline. Please rest assured we’re working urgently to resolve the issue and restore access as quickly as possible.”
To contain the incident, Colt shut down some systems, which disrupted services such as the Colt Online customer portal and its Voice API platform.
Just this morning [20 August 2025], the company provided an update to its customers, stating: “Some of our support systems, including Colt Online and our Voice API platform, continue to be unavailable and we’re very sorry for the inconvenience this may be causing.
“Our teams have been working around the clock to restore these services and will continue to do so. These services have been intentionally taken offline as a precaution following a recent cybersecurity incident.”
The attack is part of a wider wave against telecoms firms, with Orange and Bouygues Telecom recently being hit.
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