I would guess, if you have an unlocked GSM phone and wanted to use it on AT&T you can activate a SIM (at least that is what another seller is stating) and save the $30 fee at&t gets for SIM's (when I needed one from them it was only $25, it may have gone up).

But as they are I don't believe you can do anything with them, you will have to activate them and set up an account.

Probably pretty much worthless. Probably came from people who unlock AT&T phones and take the cards out of the box.