If you have an iPhone and use a AT&T SIM card and happen to live in Pennsylvania you are going to have a bad day, apparently those who meet the above criteria were recruited into “Dan” network. A local news site , Pennsylvania Live said that there has been reports from AT&T users saying that whenever they turn on their iPhone, they are welcomed by the Dan network.
One fix for the problem is to restore your phone to its original factory settings and to boot it. While other unlucky ones had to completely replace their SIM cards. This affects only those within the 717 area code and AT&T users with iPhone3, iPhone3GS and iPhone4.