iPhone users were undoubtedly excited with the release of the smartphone's iOS 7. However, several users report that the much awaited upgrade to the new generation iOS led to several problems.

According to PC Mag, one of the most reported problems encountered by iPhone users is battery drain. Users are saying that the new iOS 7 has a battery draining bug which has reduced battery life significantly.

Ars Technica claims that the transition to iOS 7 from iOS 6 has drained the battery life of several Apple devices such as the iPad Mini, the iPad 4, the iPhone 4 and the iPhone 4S. Each of these devices reportedly lost half an hour or less of battery life after the iOS upgrade. The fifth generation iPod Touch also allegedly lost 50 minutes of battery life after upgrading to iOS 7.

The results are the worst for the iPhone 5 which lost a whopping 3 hours of battery life. From its 661-minute battery life with the iOS 6, the iPhone 5 only had a 444-minute battery life with the newer iOS.

There is a suggested fix to this battery drain problem though. According to the Atlantic Wire, users can turn off the "App Background Refresh" feature as it keeps apps running and refreshing in the background. Habitual changes are also suggested such as using the smartphone less, plugging it in more and checking apps and programs that one suspects will drain the batteries.

Another problem with the iOS 7 deals with the resetting of both Gmail and Mailbox inboxes. Mailbox says that resetting the device should be able to solve the problem. They've also added that the issue might be due to the iOS 7 upgrades. As for Gmail, users are complaining about inaccurate mail count which reportedly has no fix. Others resorted to marking their messages "all read" to deal with the issue.

Sync issues were also reported by some users though the Atlantic Wire points out that such issue is normal due to server overload. In fact, the iOS 7 upgrade reportedly took down Ohio University's Internet service.

Other reported bugs with the iOS 7 include problems with the lockscreen and just recently, a bug which allows anyone to make calls to any number from an iOS 7-run phone.

According to Forbes, the emergency calling function of the iOS 7 allows for such and permits thieves to contact international and premium numbers. The bug has already been reported to Apple. According to the tech giant, the bug will be fixed with an upcoming software update.

Watch the video of the emergency calling function bug below.