Open Source Software (OSS) has substantial impact on how software-intensive firms develop products and deliver value to the customers. These companies need both strategic and operational support on how to adapt OSS as a part of their products and how to adjust processes and organizations to increase the benefits from OSS participation. This work presents the key insights from the journey that Sony Mobile has made from a company developing proprietary software to a respected member of OSS communities. We framed the experiences into an Open Source Maturity Model that includes two scenarios: engineering-driven and business-driven open source. We outline the most important decisions, roles, processes and implications. © 2017 IEEE.