Iphone 4You did not state what Iphone are you using is it iphone 5
If is Iphone 5 and the answer is NO!
But other iphone I believe you can downgrade
You can restore your iphone by downloading the following files, and pressing ALT/Option key when choosing restore on your iTunes.
Unless you've saved your SHSH blobs then unfortunately there is NO way for you to downgrade to any iOS version.http://www.sdtimes.com/blog/post/2012/09/23/How-to-roll-back-to-iOS-5-(if-necessary).aspx
i followed the steps on here and it did not work.