In 2005 (2 years before the first iPhone even hit the market) Susan Bennett had her voice recorded, under contract via her agency, to an obscure Text-To-Speech technology company, ScanSoft, later renamed Nuance Communications.
Apple acquired the license to Nuances technology and used Bennett's recordings as Siri's voice (along with years of work to take all those tiny little snippets of Bennett’s voice and know how to piece them all together in just the right way to make Siri sound so realistic), Apple’s new ‘digital assistant’ technology first launched in 2011.
Bennett didn't find out until years later that she was the voice of Siri, but Apple has never acknowledged or confirmed that information, but according to audio-forensics experts, there is a 100 percent certainty that she is.