Upon taking the SIM card out of my GoPhone, I tried to place it in another one of my AT&T phones. Sadly, this did not work, and it gave me an invalid SIM error message. I've been told that sometimes, the SIM becomes locked to the first IMEI it encounters, but that shouldn't be the case anymore. I'm told that it especially shouldn't be the case with an Alcatel phone, because its a newer model. If it just so happens to be that my SIM is locked to that phone, I'm going to be more than disappointed, considering my GoPhone quick start, and the cashier at the store, told me that I should be able to throw this SIM card wherever I want it, as long as its in an unlocked, AT&T phone.