How to open sms app via implicit intent?

Use this:

public void composeSmsMessage(String message, String phoneNumber) {
    Intent intent = new Intent(Intent.ACTION_SEND);
    intent.setData(Uri.parse("smsto:"+phoneNumber)); // This ensures only SMS apps respond
    intent.putExtra("sms_body", message);
    if (intent.resolveActivity(getPackageManager()) != null) {
        startActivity(intent);
    }
}

Official Docmentation

You can try this, it work for me:

Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_APP_MESSAGING);
startActivity(intent);

Try this:-

try {

     Intent intent = new Intent(Intent.ACTION_VIEW);     
     intent.putExtra("sms_body", message);    
     intent.setData(Uri.parse("sms:"));
     startActivity(intent);
} catch (android.content.ActivityNotFoundException anfe) {
    Log.d("Error" , "Error");
}

try this:

Intent smsIntent = new Intent(Intent.ACTION_VIEW);
smsIntent.setType("vnd.android-dir/mms-sms");
smsIntent.putExtra("address", "12125551212");
smsIntent.putExtra("sms_body","Body of Message");
startActivity(smsIntent);