http://www.mobiletelephonespy.info/mobiletelephonespyarticles/att-phone-tracking-monitor-att-network-mobile-phone-spy.htm
ATT phone tracking and monitoring can be a problem for cell phones on the AT&T carrier network. That is because some mobile phones on the ATT network have a restriction that does not allow the download or install of third party applications to the mobile device on the att network. Here is the list of mobile spy software that has no problems with at&t and which cell phone monitor software might have a problem with att phone tracking and monitoring...
Visit http://www.mobiletelephonespy.info/r/attphonetracking/ to see list of compatible att cell phone spy software