This presentation discusses the key events that have transpired from the initial technology trade study that investigated alternative solutions and associated costs, through the current state of the customization of an Intercom over Internet Protocol (IoIP) product that comprises a key US defense system. One of the critical requirements of IoIP product is to provide real-time voice communications between different security classification enclaves. Thus, the IoIP product required modification to be compliant with security directives for the protection of sensitive compartmented information within information systems (reference Director of Central Intelligence Directive [DCID] 6/3) as well as to meet other functional requirements. These new requirements for the IoIP product have continued to grow over the life of the IoIP product into a major development effort. This presentation describes how the modifications to the Commercial Off-the-Shelf (COTS) product were made while still maintaining a COTS product condition. This presentation also addresses the differences in software development, documentation and testing in a United Kingdom (UK) commercial environment. In addition, substitutes for System Requirements Review (SRR), System Design Review (SDR), Preliminary Design Review (PDR), Critical Design Review (CDR) and Test Readiness Review (TRR) are addressed as well as techniques utilized for requirements development and management, risk management, Independent Verification and Validation (IV&V). Questions related to: How does the small company manage a development effort for a large US defense industry prime contractor, what engineering and management processes were in place to ensure a success product delivery, what was learned relative to the processing of change requests, the importance of technical requirements and design documentation, was a Technical Assistance Agreement needed, what type of communications plan was in place to accommodate for the time difference, what if the small company fails during this effort, the importance of stakeholder involvement, and the role of the subcontract management are answered. This is a presentation that covers both System Engineering (SE) and Supply Chain Management (SCM) areas for the management of an international subcontract that has extensive technology development. This paper includes topics of: subcontract management, requirements development and management, risk management and some elements of program management.