iPhone stuck on "Slide for Emergency" and "Connect to iTunes" screen
By Also read: Top 10 Must Have Cydia Tweaks for iPhone, iPad, iPod touch
It mostly happened to iPhone users which recently or accidentally updated their iPhone software via iTunes. Your iPhone displays slide for emergency screen and connect to iTunes logo all the time after software update is done.
It asked you to connect the iPhone to iTunes to start activation. It should not be a problem if you have official SIM card that come along with the iPhone. But, when you connect the iPhone to iTunes with “unofficial” sim card inside, iTunes will say: “The SIM card inserted in this iPhone does not appear to be supported.“.
Why my iPhone only show slide for emergency screen?
You asked to connect the iPhone to iTunes to start activation. But, if iTunes detecs unsupported SIM card inside the iPhone, it will display this message: The SIM card inserted in this iPhone does not appear to be supported.
I hope the explanation is easily understood.
So, how to resolve this problem ?
If you are running 3.1.2 or older iPhone firmware version, you can jailbreak your iPhone using jailbreak tools which supports hacktivation. Example: Jailbreak iPhone 3.1.2 Firmware using blackra1n
If you are running 3.1.3 firmware version or iOS4 (4.0 & 4.0.1) on iPhone, you will need to activate your iPhone using official SIM card (such as AT&T sim card), or you may activate the iPhone without official SIM card (using phonebook card)
Activation 
