Through 2016 we, the Telenova team, built a lot of TELCO systems for different customers, but one of them stands out significantly. We migrated the communications of Central Cooperative Bank (CCB) to Asterisk-based open source solution Free PBX. It was installed on client's cluster based server to ensure redundancy of the communication. Again, from this point of view, the bank uses 2 SIP trunk providers. The project covers all offices and branches of the client, it's call center, has specialized software for billing A2Billing and users work with various telephones series of Yealink. The system is flexible, ensure security and allow quick and uninterrupted communication, all terminals are with auto provisoning. After large installations at our customers as Generali Bulgaria, New Bulgarian University, HomeMax and others, CCB is definitely the largest project, done by Telenova with an open source product.