30Can I unlock my iPhone to use it

30
Can I unlock my iPhone to use it on a different carrier?
Option A: Official unlock
Try calling your carrier and asking them if your iPhone is eligible for a free or paid official unlock. (In the US, AT&T now provides official unlocks for out-of-contract iPhones, and Sprint and Verizon may be willing to unlock your device as well.)

If you can get an official unlock, we recommend getting it even if you have to pay for it, since it'll be much more convenient than unofficial unlocking. An officially-unlocked device is permanently unlocked, even if you restore it and/or update the baseband.

Option B: ultrasn0w unofficial unlock
Look at your baseband version first: Find out your iPhone's baseband version by opening up your Settings app, tapping General, tapping About, and scrolling down to "Modem Firmware". That number is your baseband version. (The "baseband" is the low-level part of the iPhone that handles everything related to antennas, such as calls and 3G.)

Your device's current version of iOS doesn't matter when you're trying to unofficially unlock it with ultrasn0w. The baseband version is the important part.

If you're lucky enough to have an ultrasn0w-compatible baseband, you might just need to install ultrasn0w (search for it in Cydia). After installing ultrasn0w, you may want to install SAM to fake proper activation for your device.

Basebands currently unlockable with ultrasn0w
iPhone 4
01.59.00 (which your device only has if you haven't upgraded iOS since 4.0.2 or have preserved the baseband since then)
iPhone 3G/3GS
04.26.08
05.11.07
05.12.01
05.13.04
Special case: on any iPhone 3G, and on most iPhone 3GS except for newer ones (ones that are later than approximately 2011 week 28; you have a week 28 or later device if your serial number starts with xx128; you can use this web tool to check), you may be able to use redsn0w to flash your device to the iPad baseband (6.15.00), which permanently unlocks the device but will result in loss of GPS and warranty, and requires you to use custom firmware when restoring or upgrading your device (see this FAQ answer for more detailed information). After installing the iPad baseband, you can then use redsn0w to downgrade the device to an earlier unlockable baseband (05.13.04) that supports GPS. You should read the Dev Team's blog post about baseband downgrading for additional useful explanations, and then use the latest available version of redsn0w to perform this task. If you're just trying to install the iPad baseband: open redsn0w, click "Jailbreak", select "Install iPad baseband", and after you're done install ultrasn0w from Cydia.
Basebands currently NOT unlockable with ultrasn0w
iPhone 4
02.10.04
03.10.01
04.10.01
04.11.08
04.12.xx
Note: If your iPhone 4's baseband version is 04.10.01, 03.10.01, or 02.10.04, it may be unlockable via Gevey, which is a SIM unlocking device, but JailbreakQA does not support SIM unlocks such as Gevey. Gevey does not work on the baseband versions 04.11.08 or 04.12.xx.
Any CDMA iPhone
iPhone 3G/3GS
05.14.02
05.15.04
05.16.xx
If your device has one of these basebands, see "Special case" above.
iPhone 4S
Not supported by ultrasn0w. May be unlockable via Gevey, which is a SIM unlocking device, but JailbreakQA does not support SIM unlocks such as Gevey.
iPhone 5, 5c, 5s
Not supported by ultrasn0w.
Can I downgrade my iPhone's baseband? You generally cannot downgrade a device's baseband. The first exception is the iPad baseband downgrade (from 6.15.00 to 05.13.04) using redsn0w, explained above. The second exception is if Apple is still signing the earlier baseband, which happens at the same time as when Apple is signing the earlier version of iOS. For example, when Apple was signing both iOS 4.3.5 and iOS 5.0 at the same time (which was true during a few hours right after they released 5.0), you could upgrade to iOS 5.0 and have the 04.11.08 baseband - and then downgrade to 4.3.5 and have the 04.10.01 baseband. Apple only signs the very latest version of iOS for each device except during brief iOS version transition periods like that, so you generally can't downgrade the baseband. There's no equivalent of saved SHSH for basebands.

Option C: SAM-assisted unofficial unlock
This method no longer works to create new unlocks. If you took advantage of it during the short period when it was available, you can use it for up to three years after the unlock ticket was generated.

Option D: IMEI-based unlocking services
Depending on your phone's carrier, you may be able to find a third-party service that can provide an IMEI-based unlock for your phone. These charge a fee, which can be from $5-150+ depending on your carrier and the unlocking service. CutYourSim and AppleNBerry are established services, iProService is run by a JailbreakQA member, and there are many other reliable options available.

Just keep in mind that there are also many fake IMEI unlocking websites. Be cautious of any sites promising unlocks for all carriers, since that is not possible right now. Also be wary of sites that feature taglines such as "full support", "lifetime updates", "iOS x supported", and "members area". Pop-up video spokespeople, fake testimonials, "wait, don't leave" popups, and similar gimmicks are usually further indication the site is not legitimate. Partial list of reported fake sites.

This kind of unlock works the same as an official unlock from your carrier - it's a permanent unlock that remains even if you restore the phone and/or update the baseband.

link
This answer is marked "community wiki".
answered 10 Apr '11, 20:26

perfectpete216
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edited 21 Sep '14, 13:06

britta ♦♦
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