Jeanette Horan, IBM's chief information officer, said the decision was made because the company is concerned that the spoken data could be stored somewhere on Apple's servers. She told MIT's Technology Review (via Gizmodo) that IBM surveyed several hundreds of employees and found that many were "blissfully unaware" of what applications on their mobile devices could be security risks.
On the banning of Siri, Horan admitted that IBM is "extraordinarily conservative" when it comes to security, adding: "It's the nature of our business."
Also barred from IBM's internal servers is Apple's iCloud, which can be used to remotely back up documents and data. Instead, IBM has its employees use a company-hosted service called MyMobileHub.
Of course, IBM's conservative policies with respect to applications and serves are not limited to Apple. Third-party file transfer services like Dropbox have also been banned as the company trends toward employee-owned devices.
In fact, the so-called "consumerization" of corporate devices hasn't saved IBM any money, Horan said, because of all the security challenges that IBM faces. For example, any employee-owned device must be configured by IBM IT department to allow its data to be remotely wiped if the hardware is lost or stolen.
Apple began expanding enterprise support in its iOS mobile operating system with the release of iOS 2.0 in 2008, adding Exchange Server compatibility and other popular corporate protocols. In 2009, The Find My iPhone feature was updated with remote wipe functionality, enhancing the security of devices for both consumers and employees.