Despite the high importance of global software products' development for companies, almost no research has been done on the phase-specific barriers that companies face in this endeavor. Thus, there is a great need for studying such a multifaceted and complex phenomenon more deeply. We review applicable theories (i.e. cooperation and network theories) and analyze the extant literature on global software development and the related issues. This study provides insights to the literature by developing two integrative conceptual models, namely the globally distributed software development process and the phase-specific barriers of this process. These models are developed based on the in-depth literature review, background theories and our long practical experience in managing of international software/systems development projects in a distributed environment. The conceptual model of the phase-specific barriers may have wide applications in industrial and research settings. The implications of the findings are also discussed for research.