Key points: Effectively integrated into a complex, large-scale project. Improved the client and server parts of the VPN tunnel. We helped create mobile apps and desktop clients. As several complex tasks were to be solved in parallel, we set up several teams from specialists possessing the required skills and competencies.  It was crucial to ensure continuous operation of customer systems which required an additional NOC team working 24/7. The task was to design, monitor, set up and manage the customer\'s infrastructure, thus reducing the accident rate and making it perform at its best. At the same time our software developers have developed a package of software solutions: iOS and Android mobile clients, desktop applications, back-end and front-end parts of web applications, and also server part of the VPN-service. The tasks were properly distributed among the development teams which helped us to achieve excellent results on all fronts. Our participation in the project helped the customer to focus on promoting the product instead of wasting time on finding qualified developers and building the production process. Successful collaboration laid the foundation for long-term cooperation between our company and the customer.