[3 Ways] How to Unlock an Old AT&T iPhone (Forgotten Passcode)

You dug an old iPhone out of a drawer, charged it up, and hit two walls at once: the screen passcode you have not typed in years, and the fact that it is still tied to AT&T. People usually search "how to unlock an old AT&T iPhone" without realizing there are two separate locks, and most guides mix them up.

So let me separate them cleanly. The screen lock and the carrier lock are solved in different places, and one tool cannot do both. This guide walks through wiping the forgotten passcode, erasing the phone remotely, and requesting the official carrier unlock from AT&T.

I worked through exactly this on a hand-me-down phone a while back. I spent the first hour fighting the lock screen and wondering why nothing I tried freed the SIM, before I realised I was solving two different problems at once. Once I treated them as two steps, it took about twenty minutes total. That is the order I recommend you follow.

Part 1: The Two Locks on an Old AT&T iPhone

Before you pick a method, know which lock you are actually dealing with:

1. The screen passcode stops you getting past the lock screen. It lives on the device and is cleared by erasing the phone.
2. The carrier (SIM) lock stops the phone accepting another carrier's SIM. It lives on AT&T's side and only AT&T can remove it.

That distinction matters because a screen-unlock tool will not free the SIM, and asking AT&T to unlock the carrier will not recover a passcode you forgot. Most people need both done. The good news is that wiping the passcode also resets the phone to a fresh state, after which the carrier unlock request can be processed. These tools run on iOS 12 through iOS 27 and support iPhones and iPads right up to the current models.

It is also worth saying what does not work. The dozens of websites advertising "instant unlock by IMEI" or "bypass the passcode online" mostly want your money and your IMEI number. A screen passcode cannot be looked up from a website — the only way through it is a full erase. And a carrier lock cannot be removed by a random service; it has to come from the carrier. So this guide sticks to the three routes that actually do something.

Part 2: Method 1 — Wipe the Forgotten Screen Passcode

If you cannot get past the lock screen at all, the fastest route is FoneLab iFoneWiz, which runs on Windows and Mac. It wipes the screen passcode and can also remove a forgotten Apple ID, so a second-hand locked phone you cannot sign into becomes usable again.

Step 1Install and open FoneLab iFoneWiz, connect the iPhone to your computer with a USB cable, and choose Wipe Passcode.

Step 2Confirm the device category, type and model shown on screen, then click Start to download the matching firmware.

Step 3When the firmware is ready, click Unlock and confirm by entering 0000. The phone wipes and restarts fresh, with no passcode on the lock screen.

One honest note: wiping the passcode erases everything on the phone — there is no way to remove a passcode without erasing. It does not carrier-unlock the SIM; that is Part 4. And because the phone resets, activation lock will ask for the original Apple ID, so have that login ready.

A practical tip before you start: use the original cable if you have it, because a flaky connection mid-firmware-download can leave the phone in recovery mode. Keep the computer plugged in and do not unplug the phone while the firmware is being written. The whole process takes a few minutes once the firmware downloads — which depends on your connection — after which the phone restarts as if new, and you can set it up with your own Apple ID.

Part 3: Method 2 — Erase the Phone Remotely in iCloud Find My

If you still know the Apple ID signed into the phone and it has Find My turned on, you do not need any software at all. Erasing it from iCloud removes the passcode the same way, for free, from any browser.

Step 1Go to iCloud.com/find and sign in with the Apple ID on the phone.

Step 2Open the All Devices list at the top and pick the old iPhone.

Step 3Choose Erase This Device. Once it wipes over the network, the passcode is gone and the phone sets up fresh.

This is the free, official route, but it needs two things: you must know the Apple ID, and the phone must be online. If you cannot recall the Apple ID either, Part 2 is the route. Either way, the data on the phone is erased, so treat this as a factory reset.

Where this falls down is the Apple ID itself. If the phone was handed down to you and the previous owner never signed out, you will hit activation lock after the erase, and only that person can release it from their own iCloud account. In that common second-hand situation, Part 2 helps because it can remove the Apple ID without needing its password — which is exactly the scenario people buying a used old AT&T iPhone run into.

Part 4: Method 3 — Request the AT&T Carrier Unlock

Once the passcode is handled, the remaining lock is the SIM. Only AT&T can remove that, and they do it for free when the phone is eligible — no third-party "unlock service" can bypass it, despite what sketchy sites claim.

It usually takes a day or two for AT&T to process the request after you submit it; they will email you when it is done. You do not need to sit on the site waiting, and you can keep using the phone on AT&T in the meantime.

Step 1Open AT&T's device unlock portal at att.com/deviceunlock and choose to unlock your device.

Step 2Enter the phone's IMEI (dial *#06# to show it), confirm the request, and check your email for the unlock code.

Step 3Insert a non-AT&T SIM and follow the email steps to complete the unlock.

Eligibility usually means the account is in good standing, the phone is fully paid off, and it has been active on AT&T long enough. If you are not the original account holder, AT&T may ask the previous owner to confirm. More detail lives in this AT&T SIM unlock walkthrough.

After AT&T emails that the unlock is approved, the cleanest way to apply it is to insert another carrier's SIM and complete the setup prompts — on a Mac the phone shows up in Finder, on Windows it appears in the Apple Devices app. Once it activates on the new network, the SIM lock is gone for good and survives future updates. If approval is denied, the email usually says why (unpaid balance, not paid off) and you can fix that and reapply.

Part 5: Which Unlock Method Should You Use?

My take: do Part 2 or Part 3 to clear the passcode, then Part 4 to free the SIM. Do not pay a random website for a "carrier unlock" — AT&T issues it free when you qualify.

Part 6: FAQs about Unlocking an Old AT&T iPhone

Bottom line: separate the two locks. Clear the forgotten passcode with FoneLab iFoneWiz or a free iCloud erase, then ask AT&T to unlock the SIM. For more, see how to bypass an iPhone passcode and how to factory unlock an iPhone.

Do the two jobs in the right order and you avoid the most common headache: people wipe the phone, then realise they still need the previous owner's Apple ID to get past activation lock. If the phone was yours all along and you simply forgot the passcode, you are almost done after Part 2 or 3. If it came from someone else, spend the extra minute confirming they have removed it from their account before you wipe it. Either way, once both the passcode and the SIM lock are cleared, the old phone becomes a perfectly usable spare or travel handset on any carrier you like.