Downgrading an iPhone 4s to iOS 5 is significantly more restricted than downgrading to iOS 6. While iOS 6.1.3 remains "signed" for the 4s via an OTA (Over-The-Air) update loophole, iOS 5 is not, making an untethered downgrade impossible without SHSH blobs . Downgrade Methods
If you have never saved SHSH blobs for iOS 5 on this iPhone 4s before 2013, you cannot downgrade to iOS 5 using normal tethered methods. However, there is still one loophole: (explained in Method 2). downgrade iphone 4s to ios 5
You cannot officially downgrade an iPhone 4s to iOS 5 because Apple has stopped "signing" that firmware, which is required for a standard restore through iTunes. Downgrading an iPhone 4s to iOS 5 is
: While iMessage and iCloud were introduced in iOS 5, many server-side updates have rendered features like Siri or certain iCloud sync functions unreliable or completely broken on such an old build. Review Summary iPhone 4S still on iOS 5 - Review Jailbreak your iPhone 4s on its current version