12 Secret Codes That Unlock Hidden Features on Your Phone (2024)

Remember that scene in War Games when the code monkeys explain the concept of backdoors (i.e., secret pathways planted by programmers) to aspiring hacker Matthew Broderick? Well, as it turns out, that's actually a thing.

Coders have a storied tradition of creating back doors in programs (or sometimesjustfun little Easter eggs) that can only be accessed with a special "key." This has happened for almost as long as personal computers have existed, and the tradition continuesin the mobile age.

Excitingly, many of these backdoors aren't a secret that only programmers have access to. You can use them yourself via Unstructured Supplementary Service Data (USSD), sometimes known as "quick codes" or "feature codes." It's an extra-UI protocol that allows people to access hidden features. This protocol was originally created for GSM phones, but it's still used in many of today's 4G and 5G devices. There are also these things called Man Machine Interface (MMI) codes, which phone manufacturers make specifically for the devices they produce.

These publicly available backchannel codes (some sources claim there are 800 or more of them!) allow users to directly communicate with their service provider's computers and access back-end features in their device. They can be accessed by entering them into the phone's dialer (the screen you use to start a phone call) and usually begin and end with the * or # keys with a sequence of numbers in between. This way, there's close-to-zero chance that anyone would accidentally punch them in.

Just be warned: They're not terribly practical. Most of these codes simply surface data that the average person doesn't really need, like how nearby cell towers are performing, or what your IMEI number is (more on that later). Still, it can be fun to play around and see what unexpected functionality your phone is hiding beneath the surface. Tread carefully, though; some of these codes can be dangerous to your phone—particularly anything that says "wipe" in the title. Don't erase your smartphone just for the sake of experimentation.

Furthermore, while we would LOVE to provide you with a comprehensive list of the dozens of codes out there, doing so would be an exercise in futility. These codes seldom work across different carriers, OSes, or phone models (or even on generations of the same model). Carriers also don't want regular customers using these codes and often deactivate or change them as needed.

If you want to try them out, first do a web search of your phone's make and carrier + "USSD" or "MMI" for a tailored, comprehensive list. Don't be surprised if many of them no longer work. We attempted several codes using an iPhone 15 Pro on AT&T; and more on Motorola and Samsung handsets. The list of those that got a response on at least one device appears below. Have fun!

Field Mode: *3001#12345#*

Type this code into your phone's dialer and then press the green call button to access "Field Mode," which can give you access to info about local networks and cell towers, as well as info about your phone's signal strength. Unfortunately, this info will not reveal if someone is tapping your phone. Almost all of it is incomprehensible data meant only for technicians. To help yourself, read about how to improve signal strength.

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IMEI Display: *#06#

The International Mobile Equipment Identity number or IMEI is unique to your device and links it to a specific network. Among other things, the number can help "blacklist" stolen devices or help with customer support. If you have multiple SIM cards or a dual-SIM or eSim in your phone, you may have more than one, as shown above. On an iPhone, you can find it also in Settings > General > About but typing *#06# works across platforms, so it's faster for techs.

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Call Forwarding: *#67# and *#21#

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Call Waiting: 43 (Various Combinations)

Call waiting of course, is how you can know there's another call coming in when you're already on the phone.

In testing, I found that on AT&T using *#43# deactivated a slew of things—voice call waiting, data call waiting, fax call waiting, SMS call waiting, and sync data circuit call waiting (whatever that is)— were all disabled.I reactivated the voice call waiting specifically with 43#, and confirmed it in the iPhone's Settings > Phone >Call Waiting menu. It should be the same codes for T-Mobile.

On Verizon, using *43 will deactivate Call Forwarding, not Call Waiting; *42 will turn it back on. To temporarily stop Call Waiting on Verizon, use *70 before the 10-digit number you call.

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Available Minutes: 646

The 646 on the keypad also spells out "MIN." With an iPhone on AT&T, the code returned an SMS text message to the phone revealing how many minutes are still available. Same on Android: Instead of showing the info on a new screen, it sent a text. AT&T specifically spells out using code *646# to check rollover minutes; it also offers an option for Spanish speakers via *876#. Verizon says to use #646; T-Mobile uses #646#.

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Bill Balance: 225

This is another one that doesn't bring up a hidden screen but instead sends a text message with your current billing balance due—225 spells BAL. For AT&T use *225#. On Verizon, it's #225. T-Mobile users use #225#.

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Billing Cycle: 3282

This prompts an SMS message with billing info such as when the billing cycle started, total plan usage (even by line if your account has more than one), and if you've gone over your data allotment. 3282 spells DATA.

Like above, each carrier has its own format: AT&T: *3282# and Verizon: #3282. T-Mobile goes with #932#.

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Caller ID: #31#

Entering this code brought up a screen stating that my Caller ID (also known as Calling Number Display or CND) had been disabled. In order to re-instate Caller ID, enter *31# or do it under Settings > Phone on iPhone.

This code may be better known to some people to block caller ID on a per-call basis. Type #31# (or the more familiar *67) before you put in a person's 10-digit number. What you enter would look like #31#1234567890. This is a must on landlines where you can't turn off Caller ID without asking customer service.

If you have caller ID turned off all the time on your mobile device, re-activate on a single call by putting in *82 in front of the number.

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Test Alert Status: *5005*25371#

Dialing this will tell you if your phone is set up to receive test alerts from the government and emergency services. Again, this isn't for the actual alerts—it's just to test if you can get them. Dialing the number above will give you a yes or no; if it's on and you want it off, dial *5005*25370# and hit the call button to deactivate.

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Check Account Balance: *777# (Prepaid) or *225# (Contract)

If you've got a prepaid phone, dialing *777# and hitting the call button generates a text message showing how much you have left. If you don't have a prepaid phone, it'll say you have the wrong type of account (see below). Instead, use *225# to look up what you owe.

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Android Phone Stats: *#*#4636#*#*

This brings up a Testing settings panel with 5G/LTE debugging info, phone information, usage statistics, Wi-Fi information, and NFC settings. How much of it you can understand is up to you.

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Wipe Your Android Device: *2767*3855#

We did not test this one. If you type it into an Android device, it reportedly performs a full factory reset/restore, even re-installing the phone's original firmware.

Do you know some dialer codes that work on modern smartphones that we missed? If so, leave them in the comments below!

Evan Dashevsky contributed to this story.