Siri is well-known voice control system so; in this regard here I am going to present that how you are able to install Siri in your iPod touch and iPhone 4 on the time when you are using iOS 5. But here I’d like to give the credit to RedmondPie for this kind of tutorial and for images. Below you can see that how to install Siri on iPhone 4 and iPod Touch using iOS 5.

Step 1: Firstly Jailbreak your iPhone/iPod touch on iOS 5 using Redsn0w or Sn0wbreeze.

Step 2: Now you have to download files required for the Siri port to iPhone 4 and iPod touch 4G. You will have to find these files yourself as we won’t be able to share these files with you.

Step 3: To use a file explorer for your iOS device, copy over the AssistantServices.frameworkfolder you downloaded in Step 2 to Root > System > Library > PrivateFrameworks after plugging in your device to your computer via USB.

Step 4: Transfer all files from the Springboard folder in Step 2 to Root > System > Library > CoreServices > Springboard.app on your iOS device.

Step 5: Using iFile (you can get it from Cydia), open the .plist file for your iOS device fromSystem > Library > CoreServices > Springboard.app. It will be named N81AP for iPod touch 4G and N9x for iPhone 4 (where x may be 0, 1, 2).

Step 6: Add a new property list named assistant to the .plist file and set its class as Booleanwhile setting its value as YES.

Step 7: Add the following to the .plist file:

<key>assistant</key><true/>

Step 8: Respring your iOS device.

For more info you can check out the below video…

You have to follow all the above steps at your own risk because we aren’t responsible if you have to face any kind of damage.