Siri was founded in the year 2007 by Dag Kittlaus (CEO), Adam Cheyer (VP Engineering), and Tom Gruber (CTO/VP Design) .
Siri is now an integrated part of iOS 5, and available only on the iPhone 4S
It is an intelligent and personal (PA).by way of using natural language user to answer ,raise song,play audio,video,volume control,go to internet etc...........
HOW TO INSTALL SIRI
STEP 1: Initially need an or iPod touch which is running iOS 5 / iOS 5.0.1. You can check your iOS here.
STEP 2: You’ll need to do jailbreak your iPhone 4 or iPod touch 4G by using our guide posted here for iOS 4.
STEP 3: Once jail broken is done , head to Cydia then Manage, Sources, Edit and finally hit the Add.
STEP 4: Write the following some repository and hit add:
STEP 5: return back to your Cydia and then search for H1Siri and it on your phone . It will take some time to appear since it weighs 109 MB.
STEP 6: After successful installation, give your device a reboot.
STEP 7: Now go to , General, Siri and switch it to on.