With over 20 years’ experience, and the most comprehensive Pan-European network, Colt is the ISDN provider of choice for thousands of businesses across Europe.

Work with us to consolidate and simplify your voice services while reducing supplier costs. Shifting to Colt is easy. We minimise disruption to your business from set-up then guarantee to maintain service.

Cost Effective & Reliable

One network and one supplier means one, reduced flat fee. You can also make extra cost-savings by moving to VoIP. Ask our experts how. Our network is business-grade and robust. If the unexpected happens, your business will continue to run with our Disaster Recovery service.


With our Diamond Telecoms Expense Management tool you have complete visibility of call spend and traffic. This helps you see and manage costs better.

Because we fully own and operate our own network across 50 geographically diverse, carrier grade switches we can guarantee you a seamless experience across Europe.

It’s easy to change to Colt ISDN services


We have our own number pool across Europe as well as extensive porting capabilities. Keep your current numbers, or add new ranges, with no disruption to the business.

Control your telecoms spend with our competitive flat fee. We offer All Inclusive, Pre-Pay, and Pay-As-You-Go tariffs to suit customers of all sizes and traffic levels.

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Case Study

Case study Alpargatas

Well known for their famous Havaiana flip-flops, Alpargatas is an Brazilian footwear manufacturer who uses Colt network services.

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Meet Ali, Technical Coordinator

“The best aspect of my job is that it gives me a full understanding of the network and processes around it, from order entry to billing. Colt has offered me a platform to learn and gain practical experience about innovative technology, but also offered me the opportunity to deliver for customers who rely on us.”

Careers at Colt
As VoIP gains more acceptance and demand increases, we’re confident that Colt is well equipped to accommodate our growth and will continue to provide us with the excellent support we always receive. Intercall
VP Telecoms EMEA, Intercall