I have already gone through the sample code present in the Android SDK. It tells that you should have voice recognition APK in your device. I tried a lot but could not find
Update:
According to this article, Google Voice Search is what you actually need.
The Android SDK makes it easy to integrate speech input directly into your own application—just copy and paste from this sample application to get started. Android is an open platform, so your application can potentially make use of any speech recognition service on the device that's registered to receive a RecognizerIntent. Google's Voice Search application, which is pre-installed on many Android devices, responds to a RecognizerIntent by displaying the "Speak now" dialog and streaming audio to Google's servers—the same servers used when a user taps the microphone button on the search widget or the voice-enabled keyboard. (You can check if Voice Search is installed in Settings ➝ Applications ➝ Manage applications.)
I've used the sample of STT without problems. How they said previously, you have to download it from the Market.
Regards