How to make a iphone 3gs firmware check?

Hi, You can download iPhone OS 3.1 to check the firmware before taking it out of the package. Apple introduced iPhone OS 3.1 for iPhone and iPod touch(OS 3.1.1), delivering enhancements and fixes (including security fixes), onboth platforms. A good news for iPod Touch users is that they can also downloadiPhone 3.1 firmware for free.You can download & then install the new OS 3.1by clicking on “check for update” button right from the iTunes software. Makesure you have the latest iTunes 9 installed in order to upgrade the OS to 3.1.Youcan download it from news softpedia.com, idownloadblog.com , techpp.com thedownload will be free of cost if you download it from these sites.I am sureafter visiting above mentioned links you will able to download it free of costand easly with out any problem.