Professor Caelli is the Head of the new School of Software Engineering and Data Communications in the Faculty of Information Technology at the Queensland University of Technology. He is a Computerworld nominated "Pioneer" of the Australian IT industry with some 40 years involvement in the area, 27 years of which have been in IT security and cryptography.

He has served as a representative of the Australian Computer Society to Technical Committee 11 (Privacy and Security in Information Processing Systems) of the International Federation for Information Processing (IFIP) and received the IFIP "Silver Core" award for his work in information security in the international area in 1992. He served as Chairman of that committee for over 5 years.

Bill was a Founder of ERACOM Pty Ltd in 1979 which developed, manufactured and marketed Australian designed small computer systems and cryptographic sub-systems, including the first encryption board for the IBM PC and high speed cryptographic security modules. He served on the early Standards Australia committees responsible for the creation of cryptographic standards for the electronic funds transfer (EFT) sector. He has a PhD in Nuclear Physics from the Australian National University.