Hi, there
What is Airdrop?
Airdrop is a new function of iOS 7, which handles swift file transfer between iOS devices. However, it should be noted that not all iOS devices can use this function. At present, Airdrop is provided only on iPhone 5, iPad 4, iPad mini and iPod Touch 5. They need to use iCloud account. In other words, iPhone 4S and its contemporary products do not support AirDrop.
Hope it can help you.
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iPhone Data Recovery, you can read more here.