In a support article, Apple has acknowledged the problem saying that if an Exchange user responds to an exception to a recurring Calendar event with a Microsoft Exchange account on a device running iOS 6.1, the device may begin to generate excessive communication with Microsoft Exchange Server, resulting in increased network activity or reduced battery life on the iOS device and that the extra network activity will also show up in the logs on Exchange Server, leading to the server blocking the iOS device.
Apple has advised that users can avoid this bug by not responding to an exception (change to a single instance of a repeating calendar event) to a recurring event on their iOS device, until a patch is issued. It has also recommended that users can turn off Calendars from their Exchange account for a period of 10 seconds and turn them back on if they do respond to an exception and encounter the bug.
Earlier, Microsoft had also issued a support document advising administrators and users to not process Calendar items such as meeting requests on iOS 6.1 devices, and to immediately restart the iOS 6.1 device. It had also recommended removal and reactivation of the device partnership with the server, creating a custom throttling policy for iOS 6.1 users, and blocking iOS 6.1 users on the server.
Apple released iOS 6.1 on January 28. The update added LTE support for various carries around the world and, for users in the US, the ability to purchase movie tickets through Fandango with Siri. Other new features included a new option to reset the Advertising identifier and offering iTunes Match subscribers the ability to download individual songs to their iOS devices. Also included were redesigned playback controls on the lockscreen, minor changes in Safari and slight changes to boarding passes in Apple's Passbook software.