Apple has issued five separate notes detailing known issues with its iPhone, as well as some instructional material on using the device. One note explains a potential problem where users are unable to send mail when using an email provider other than Yahoo Mail, Gmail, .Mac, or AOL. A second note covers users experiencing iPhones that aren't recognized in iTunes for Mac OS X, while a third note explains what actions to take when the iPhone is frozen or unresponsive. Two more notes explain SMS text messages and connecting to the internet with EDGE or Wi-Fi technology.