I bought my iPhone 4S from Sprint last December, and when I was buying I specifically asked the sales rep if I would be able to use my phone with a European SIM card (I'm an international university student here in the US). He said yes, as long as I was a customer in good standing for over 3 months, and that I would need to call Sprint and they'd do everything for me.
It's now June, and I'm set to head home for summer holidays at the end of this week. I called customer service today, and after a somewhat long conversation found out that it's not possible to unlock the SIM slot in my iPhone because I have ASL on my account. They said that nothing can be done, and that they're sorry the sales representative gave me the wrong information, but ASL can't be removed, and my iPhone can't be unlocked without it.
Had I known that this would be the case (or had the sales rep told me so), I wouldn't have bought my phone from Sprint, I would've just gone and bought it from Apple – I know it's more expensive upfront, but the abillity to use my phone with local SIMs abroad is vital to me, since I happen to be from abroad.
Is there any way to have my ASL lifted? I've been paying my bills on time, and I'm coming back to America in Autumn, it's not like I'm going to run away.
Perhaps there is no routine procedure, but if I explained my situation to someone, they would be able to do it?
2nd - Call sprint again (I know what you are thinking but...) and ask to be transferred to ACCOUNT SERVICES. Talk to them, if needed, if it's ok for you, maybe prepay one month to see if they can drop ASL, or at least place a note in the account so you can unlock it.
3rd - If nothing works, you can jailbreak it, they have the new jailbreak out for the 5.11, very easy to do, but I hope it will not come down to this last resource.
I hope everything works out for you, and enjoy your trip home