Contact that person if it's a corporate environment. Perhaps they've experienced similar issues with other iPhone users on the same system.
ATT Wireless forums is another good place to receive help for this stuff IME and O. You may have to register, but it only takes a minute.
http://forums.wireless.att.com/
I am experiencing isues with receiving calls when my email is activiated. 3 new iPhones, 2 new sim cards and 3 different numbers...
as soon as I connect my mail, phone calls go directly to voicemail and the phone does not ring,there is no record of the call and text messages show up anywhere from 2 hours to 12 hours after they are sent to me. The ATT techs indicate that their network shows that the calls are going to voicemail so they "fix" it and it then reverts back to the same issue within minutes. Other iPhone users are connecting to the same exchange server and not having problems. I have duplicated their settings... they get calls and I don't...
VERY FRUSTRATED... any suggestions???

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