Although a few weeks have passed since Halloween, it's never too late to play a party for your friends. An idea would be the use of special effects for voice for telephone conversations with these (along with which we also recommend hiding phone numbers, so that they are not warned who is the person calling them). Although there are more Applications For various mobile operating systems that allow users to modify the voice, they must configured before starting the conversation, and the voice cannot be changed back during it.
VoiceChanger It's a tweak for iPhone, available in store-ul Cydia, which allows users to use a range of special effects funny to change the voice, and in addition these can be applied live and modified during telephone conversations.
After installing the tweak, it can be configured via the stock app Settings (ENABLE and Disable). Then, in Voice Effect, users can choose one of four special effects funny, and also can normalize the voice in real time. The options provided by the tweak are Dark Lord, Tenor, Normal-No Effect, Smurf and Rumplestiltskin.

The application costs 2.99$ and can be downloaded from Cydia Store (it is only available for jailbroken iPhones). It is also only compatible with iPhone 4S and iPhone 5.
STEALTH SETTINGS – Apply voice live effects during calls on iPhone with VoiceChanger