rge vertical industry enterprises want to maintain a strong control over innovative software-supported services and keep a major part of their software development in-house. This especially applies to industries where technology or process innova- tions play an important role, such as the car industry, some other manufacturing and electronic industries as well as opportunity seeking service industries. In terms of visible revenues, the secondary software industry is considerably worse than the primary software industry, as the added value of the software is sold along with a hardware product (e.g., a mobile phone) or included in the price of a service (e.g., banking service fees). The evolution may also be halted in the early phases if the market size is insufficient to attract enough competition to the segment, or if the dominating companies are unwilling to proceed. Especially in specific market niches of manufacturing industries, some of the dominating players are unwilling to open their software interfaces for open competition. Overview of Telecom Operator Software Market Eetu Luoma, Lauri Frank, and Mirja Pulkkinen Telecommunications is an essential enabler of modern societies and a global vertical industry, providing communication and information services, with its annual reve- nue of over trillion euros. In this book, a company providing these services is referred to as a telecom operator or communications service provider (CSP). CSPs create value by offering connectivity to and via an infrastructure of networks for transferring signals. The core business processes in a telecom operator company therefore revolve, on one hand, around physical networks and their maintenance, and on the other, managing their customers and their use of the connectivity services over the networks. In the past, CSPs' operations focused more on the development and management of network infrastructure. Eventually, as the need for standardization of the systems and operations became apparent, International Telecommunication Union (