EditText editText = (EditText) findViewById(R.id.editText);
    String myNum = editText.getText().toString();


    try {
        SmsManager smsManager = SmsManager.getDefault();
        smsManager.sendTextMessage(myNum, null, "Wake Up!", null, null);
        Toast.makeText(getApplicationContext(), "SMS Sent!",
                Toast.LENGTH_LONG).show();
    } catch (Exception e) {
        Toast.makeText(getApplicationContext(),
                "SMS faild, please try again later!",
                Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }