iPhone Push Notification - How to use default sound

I have implemented whole push notification service for my application using easyapns.

I have implemented the server part using php and using the default php classes provided by easyapns.

Now, from server (php file), i am passing sound file name like :

$apns->addMessageSound('bingbong.aiff');

And I am including this 'bingbong.aiff' file in iPhone's Resource folder.

But Now I have a query that is it possible to play a default in-built sound of iPhone device instead of specify it externally ?

Thanks开发者_开发问答 in advance....

Normally $apns->addMessageSound('default'); should do the trick.