Tactical communications systems have traditionally been acquired as if they were weapons systems, lengthy requirements definition phases were followed by even lengthier development phases, followed by an extensive testing period that was based on original requirements. With the technology available in the 1970s during the Tri-Service (TRI-TAC) switching systems' original development, this approach was necessary to meet the services' unique switched system needs. Under this early approach, different circuit switch types were developed. Theses switches were tested in very rigid environments by engineers, using very well-defined test procedures. This resulted in switched systems that tested well, bur still contained many bugs that were identified during user deployments. In the late 1980s and early 1990s, switch derivatives were developed that while similar to the original systems, could not be rested using the same approach. The most recent upgrade leveraged a common software baseline across different hardware platforms, and required a very different approach to testing the systems.