Why wont my iphone3g update

[Perplle]

Hi everyone I am having a problem with my iPhone 3G I wanna use it for my car like an iPod to have in the glove department I got it jailbroke using greenpoison and it's on 4.2.1 I connected it with iTunes and restored it to original settings and it says it's at it current update it won't let me update to the latest one why ?

 

[iGaz]

4.2.1 is the last one for the 3G. Apple stopped issuing updates for it...

 

[Gregoris]

no more firmwares for the iphone 3g... another forgotten about device from apple

 

[Perplle]

no more firmwares for the iphone 3g... another forgotten about device from apple

O okay thanks guys