Why Siri will not work on older devices?

It seems that the secretary Siri holds more secrets about how they work and why Apple has to allocate this service for IPHONE 4, not as I would have stayed devices? Well it seems that he is not about only by Alsovetoar, but also it also relates to Hardware where this sensor is equipped with the secretary under the rays of red and interest here so you know you keep a phone in preparation for questions on them.


Of course, IR iPhone the old also has the same sensor is next to the sensor lighting also but Broken only when you receive the call either a Phone Call Basic or phone call over the Internet and that marks activated with sensor movement, and then turns off the screen as they approach the phone from your face even accused of doing by clicking on the buttons by mistake, while mobile phone iPhone 4S he has a new design for the IR sensor works all the time and Siri also teaches about whether they are ready to answer or not.
[iFixit]