BitSMS Delivery Confirmation with AT&T

I've searched all over the forums, both here and over at a cell phone forum, and can't seem to track down an answer for this.

I found that unfortunately AT&T doesn't support the low level SMS Delivery Confirmation commands, so the iPhoneDelivery app won't work.

Supposedly, there's another way to do this that involves adding a carrier-specific prefix to your message. It indicates to the carrier that you wish to be informed when a text has been delivered. Unfortunately, I can't seem to find what AT&T's prefix is. Has anyone here on BiteSMS with AT&T successfully gotten this feature to work?

 

Why would you be glad that your carrier doesn't support a useful feature?

The other part you describe is the prefix I mentioned, and does supposedly indicate true delivery confirmation (not the useless implementation you describe). However, AT&T won't provide it so I was asking if someone here knew what it was.