This is a very good question from gahwhatever and to go further i would like a recipt notification. There is no way to make sure a SMS was read even if received...in some cases i need to know if my SMS is read and not only receive which makes a big difference.
All other cells i had add the receipt notification which means you get a notification once the person has opened the SMS you sent him...
Why in the hell this is not on the iPhone...are they going to release it in 3.2 and make a big thing out of a very old and comon option...as they ridiculously did for copy/paste and MMS....come on Apple...get up to date with simple things...
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