The major barrier to corporate adoption, cited analysts say, is that the iPhone still does not work well with corporate e-mail systems, which normally use technology such as Microsoft's Exchange Server and Outlook to deliver push mail. Similarly, users cannot have contacts and calendars updated via EDGE or Wi-Fi; this is taken for granted on Windows Mobile phones. "What really made the iPod take off was when they made it compatible with Windows," says American Technology Research analyst Shaw Wu. "So if they made the iPhone compatible with Windows e-mail, meaning Outlook, that would really make sales take off." Some business clients are said to be holding out for the promised 3G iPhone, while others complain that typing out more than a quick e-mail is troublesome on the device's touchscreen.