private static final String ACTION_SENT = "sent";

…

final Intent sentIntent = new Intent(ACTION_SENT);
final PendingIntent sentPendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 0, sentIntent,
        PendingIntent.FLAG_UPDATE_CURRENT);

registerReceiver(new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String result = "";

        switch (getResultCode()) {
        case Activity.RESULT_OK:
            result = "Transmission successful";
            break;
        case SmsManager.RESULT_ERROR_GENERIC_FAILURE:
            result = "Transmission failed";
            break;
        case SmsManager.RESULT_ERROR_RADIO_OFF:
            result = "Radio off";
            break;
        case SmsManager.RESULT_ERROR_NULL_PDU:
            result = "No PDU defined";
            break;
        case SmsManager.RESULT_ERROR_NO_SERVICE:
            result = "No service";
            break;
        }

        Toast.makeText(getApplicationContext(), result, Toast.LENGTH_LONG).show();
    }
}, new IntentFilter(ACTION_SENT));

…

smsManager.sendTextMessage("…", null, "…", sentPendingIntent, null);