If you put your SIM card from your old phone into your new iphone 3G or 3GS you got from eBay will you be charged any kind of fee for upgrading to a new phone?

No, however you must keep in mind that AT&T requires a special data package for iPhone to be added on your account. Without this additional package, the iPhone will not functi (MORE)

Can you jailbreak an iPhone 3gs on 4.1 firmware?

Here's a guide on how to jailbreak your iPhone iPod or iPad ios 4.2.1 and all previous models: http://reviews.ebay.com/How-to-Jailbreak-Your-iPhone-4G-iTouch-or-iPad-4-2-1 (MORE)

How do you upgrade firmware on iPhone 3gs?

software updates for the iphones, ipads, and ipods all use itunes. the 3gs is capable of running apple's newest 5.0.1 software which brings icloud, notification center, and (MORE)