FalWok Turbo  Ultra S for GSM iPhone 4S iOS 5.1 TO 6.1.3 Unlock Sim card Use all carrier 

Quick Overview

The FALWOK Ultra S GSM unlocks your GSM iPhone 4S running iOS 6.1.3! It's a true plug-and-play unlock for GSM iPhone 4S running iOS 5.1 - 6.1.3. The FALWOK Ultra S is a thin microprocessor that sits between your network SIM card and the base-band hardware, allowing you to use your GSM iPhone 4S on all worldwide GSM networks

FALWOK? Ultra S Notice 

The FALWOK? Ultra S for iPhone 4S iOS 6.1.3 does not fully support MMS functionality in GSM iPhones. Due to the way MMS settings are locks within iOS 6.1.3, there are limitations on manually inputted settings. iFunBot, IBackUpBot, and Jailbreak have been used in previous iOS versions to manually program SMS and MMS settings and circumvent this issue. Applenberry.com cannot guarantee a solution will be made available for this issue with the FALWOK? Ultra S for iPhone 4S iOS 6.1.3.