iPhone 3G (US) firmware upgrade help
first off im new to the whole upgrading and jail-breaking of iphones and the such, but was recently givin a US iphone 3g by a friend. Im wanting to update the firmware on it and have been trying to find information on the web before i go threw with it. I tryed to update threw the iTunes program as all have no luck. i have tryed manually updating threw itunes via the shit+restore to select the ipsw but a) says the current iPhone software is up to date @ 3.1.3 b) when i try to upgrade using latest official 4.2.1 ipws it says its not compatible.
Any help or pointing me in the right direction would be appreciated.
Phone: iPhone 3G
Version: 3.1.3 (7E18)
Modem Firmware: 04.05.04_G
Unlocked: No (Believe not due to the restore)
Jailbroken: No (Believe not due to the restore)
Computer OS: Windows 7 Ultimate
Im going to make the assumption that i need to upgrade the modem firmware first (i assume i will have to eventually) before updating the version firmware, but again this is an assumption.
Im also outside of the states, but am using latest version of itunes, and have restored phone to base 3.1.3 setting using the itunes software in preparation for the upgrade.
Any help, or pointing me in the right direction (other related posts etc) would be appreceated.
Thanks in advance