Intent sendIntent = new Intent(Intent.ACTION_VIEW);
sendIntent.putExtra("sms_body", "Your Message");
sendIntent.setType("vnd.android-dir/mms-sms");
startActivity(sendIntent);

With above code we can easily launch the sms screen using intents.
Now just we give mobile number in To:Edit field.

Here is another way:

SmsManager m = SmsManager.getDefault();
String destination = "xxxxxxxxxxx";
String text = "Hello, you!";
m.sendTextMessage(destination, null, text, null, null);

(from http://www.devandro.com)

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Android training online videos: http://android.voxisland.com
Jay