Is my iPhone unlockable?

Below is a quick reference for you to check whether your iPhone can be jailbroken
or unlocked as of today 02/11/2011. Hope it will help

 

Model	Firmware	Baseband	Jailbreak	Unlock
iPhone 4	4.0.2 or below	01.59.00 or below	YES	YES
	4.1, 4.2.1	02.10.04 or above	YES	NO
iPhone 3GS	ANY	ANY	YES	YES
iPhone 3G	ANY	ANY	YES	YES
iPhone 2G	ANY	ANY	YES	YES

 

 

Difference between iPhone 4 GSM model and CDMA model

Support up to five calls simultaneously

Feature	iPhone 4(GSM)	iPhone 4(CDMA)	Notes
Call forwarding	Turn on or off in Settings -> Phone	Dial *72 plus forwarding phone number to turn on. Dail *73 to turn off
Call waiting	Turn on or off in Settings -> Phone	Dial *70 plus the number you are dialing. Dial *70 each time to disable call waiting
Caller ID	Turn on or off in Settings -> Phone	Dial *67 plus the number you are dialing. Dial *67 each time to disable Caller ID
Conference Calls	Support up to two calls simultaneously	CDMA network may not be able to add, swap, or merge calls in certain situations
Dial a soft pause	Tap and hold * when dialing. When editing a contact number, tap +*# and then tap "pause"	Tap and hold * when dialing. When editing a contact number, tap +*# and then tap "pause"	Inserts "." into a phone number. Waits a few seconds before dialing additional digits
Dial a hard pause	N/A	Tap and hold # when dialing. When editing a contact number, tap +*# and then tap "wait".	Inserts ";" into a phone number. Waits for the user to tap Dail before dialing the additional digits entered after ";"
Place a call on hold	Tap and hold Mute	N/A	CDMA network do not offer the ability to place a call on hold

How to enable AirPrint for Any Printer

AirPrint is the new feature introduced on latest iOS 4.2 such that you may print documents from your iPhone/iPad/iPod Touch to an AirPrint compatible Printer. However, there are only very few printers that are compatible with AirPrint. You may follow the steps below to enable AirPrint for almost any printer:

• You will need to share your LAN/Local Printer from your Windows PC
• Download AirPrint driver from here
• Extract it to C:\Program Files\AirPrint
• Choose Start -> Run and type cmd
• Type the following in the console and enter:
  sc create AirPrint binPath= "C:\Program Files\AirPrint\airprint.exe -s" depend= "Bonjour Service" start= auto
• Type sc start AirPrint in the console and enter.
• Now try to print it from your iPhone!