How To Get Galaxy S4 S-Voice onto your Android Phone
How to Install Galaxy S Voice
Download S Voice's APK file from the download link here.
Copy the downloaded file to your device.
Go to Setting » Security menu on the device, make sure you Enable "Unknown sources". So that you can manually install apps from the SD card.
On Android 4.2, you'll have to first unhide the Developer options menu by going into Settings » About phone then clicking on the Build Number field seven times.
S-Voice APK (Size: 25.21MB)
Thanks to SamMobile