Q: Why Jailbreak & Unlock?
Unlock your phone to all networks. So if you're not on an official carrier that supports your phone, you can unlock it to use with any carrier in the world. You can download thousands of apps directly to your iPhone for FREE!!! Use Facetime feature on iPhone 4 over 3g signal. Access to Apps not offered in the iTune App Store. Custom themes and fonts! The ability to modify the iphone to the max to the way you love. Use your iPhone as a WIFI hotspot! Assign your own ring tones and SMS tones! View Calendar/Weather on the lock screen. Play vintage video games from Nintendo, Super Nintendo, GameBoy, Genesis, etc and much much more... In short, you can discover iDevices' full potential which you wouldn't if you jailbreak your device.
Q: Would it void the warranty?
NO - it wont. You can simply restore in iTunes and you are back to normal!!
