C1 is the global technology solution provider elevating connected human experiences. Over 6,000 customers use C1 to help them build meaningful connections.

With over 25 years of knowledge and experience, we offer custom construction services to suit your unique needs and desires. After a life-altering event, we’re here to help. Our commitment to …

Your future business starts here. C1 is a platform that connects you to the global digital economy through innovative products and services. We make it simple to build your entrepreneurial journey …

A C1 learner can use English effectively for work, study, and academic purposes. Writing is well-structured, detailed, and stylistically appropriate. Vocabulary includes idiomatic expressions and …

If you are a C1 level English user, you can understand a wide range of complex texts and express yourself fluently. Read more about this level.

Learn more about C1 Advanced – proof of high-level English skills for study and work, accepted by more than 11,000 institutions worldwide.

Learners who achieve C1 Advanced level can understand a wide range of long, complex texts. They can interact and express themselves fluently and spontaneously and use language flexibly and effectively …

C1 Advanced looks to prove high-level achievement in English and is designed for learners preparing for university or professional life. It focuses on Level C1 of the Common European Framework of …

Explore C1’s end-to-end technology services—including IT, communications, and customer experience—spanning advisory, professional, and managed solutions. From enterprises to small …

Get instant global PSTN access with long distance in 234 countries and local presence numbers in 54 countries on a secure, compliant and reliable voice network. Filter out unwanted calls, maintain e911 …