In December 2007, SRI launched a spin-off company, Siri, Inc., which Apple acquired in April 2010.[98] In October 2011, Apple announced the Siri personal assistant as an integrated feature of the Apple iPhone 4S.[99] Siri's technology was born from SRI's work on the DARPA-funded CALO project, described by SRI as the largest artificial intelligence project ever launched.[100] Siri was co-founded in December 2007 by Dag Kittlaus (CEO), Adam Cheyer (vice president, engineering), and Tom Gruber (CTO/vice president, design), together with Norman Winarsky (vice president of SRI Ventures). Investors included Menlo Ventures and Morgenthaler Ventures.[101]