? The iPhone could not be restored. This device isn't eligible for the requested build. ?

First question for you:

Has this phone ever been jailbroken or hacked to unlock it from a carrier?

The error you mention is very common for devices in those categories.

Sounds like you are trying to restore to a version that is no longer signed by Apple. You will only be able to restore to 6.1.3 as that is the current version for the 3GS.

working with .ipsw files means you are having a jailbroken phone.

Or at least trying to restore an older version of iOS, after using Tinyumbrella.

Now your computer hosts file is changed and the restore will not work.

Tell what it is, is it only Tinyumbrella or is it jailbreaked?

If it is officially unlocked, then restore should not be a problem.

If is unlocked by AT&T it is OK, if it is unlocked in the shop it is probably unlocked by a hack: that works, but you can not restore or update after that.

We can see what is in the hosts file, but that means going a bit deeper in your mac (or PC), are you prepared for that?

Put it in your Dropbox/Public folder and leave it there, send us the link here.

Where EXACTLY did you get the IPSW file you're trying to use? Delete any you have. Plug the phone into your computer running iTunes. If you are not prompted to update it, click the 'check for updates' button in iTunes. Let iTunes download the current version from Apple and install it.

You are def downloading the wrong file, from the wrong place.

Then find a better network connection. Either the file you have has been "customized" or is corrupt.

Patrick you are on the wrong road....

Why do you want an ipsw file from the wrong site? why not standard from iTunes?

iTunes download is not better or worse than other downloads.