This document fulfils the requirements for the final Thesis in completion of an Engineering Doctorate program at the University of Southampton. This Thesis presents the findings of a three and a half year Engineering Doctorate study (2003-2007) which investigated the options for open source in delivering Operational Support Systems (OSS) to the global telecommunications industry. The principal mode of investigation has been Action Research in collaboration with a number of industry players and in support of the New Generation Operations Support Systems (NGOSS) standardisation activities conducted under the auspices of the Telemanagement Forum (www.tmforum.org). The thesis considers the use of open source to expedite the creation and dissemination of emerging ass standards through a number of collaborative industrial projects including a Next Generation Network proof .' ofconcept and a novel application ofNGOSS to the problem ofmanaging a digital TV network. Conclusions are drawn as to the benefits which service providers could derive from using open source as a key factor in managing the strategic risks and costs associated with the new product introduction process. The principal contribution has been to develop within the telecommunications industry a greater understanding and acceptance ofthe role which open source can have in the delivery ofOSS solutions. Keywords Open Source, NGOSS, OSS/J, Action Research, ass, Operations Support Systems, Systems Integration, Requirements Management, Network Management, Digital TV