I know many people will not even know what I am talking about so I will stop and explain. A few years ago when I used T-Mobile there was a beautiful option on my 7100t that allowed me to know when a person received a text message. This option is built into the GSM protocol and can be implemented by each carrier. It does not tell you when a user reads a message but just that it was delivered. This was a great way for me to find out if a person was in coverage or in the subway and let me know when they got out. 
AT&T does not allow this protocol. I do not know why but maybe the overhead of one extra return text message…
You can see that this option is available when you put a T-Mobile SIM card in your phone. It will show up in Settings>SMS.
AT&T could you pretty please implement this code? Anybody manage to get something along these lines to work on AT&T?
If you are interested in the specifics or just like to know everything check out the full explanation at the link below:
