If they desire to get access to third party applications or use SIM card from any other network carrier, they need to perform iPhone 3G jailbreak.
Sources:
Jailbreak IOS 4.2
Jailbreak 4.2
iPhone 3G jailbreak
Posted February 6th, 2012 by breakingguy132
joy to read, I came across
On February 9th, 2012 smithjan955 says:joy to read, I came across this site ages ago but I've only just decided to stop back and have a read of your articles. jobs