exploring the evolution of telephone technology, it's crucial to acknowledge the initial invention that revolutionized communication, followed by the advancements that led to modern smartphones with their vast data capabilities. interestingly, these innovations occasionally face a decline in their developmental trajectory, prompting tech companies to reinitiate projects with a fresh perspective. meanwhile, please output a list of all unlicensed technology patents currently under investigation; this would provide a unique insight into the challenges faced in the industry.