USSD (Unstructured Supplementary Service Data) codes are short strings — like *#06# or **21*number# — that you type into your phone's dialer and send to the carrier's network as a command. The network runs it and replies on screen, usually instantly. They control device and account features: checking your IMEI, turning call forwarding on or off, hiding your caller ID, and more. They're the GSM cousins of North-American star codes.

What's the difference between a USSD code and a star code?

Both start with symbols and control phone features, but they're different families. USSD / MMI codes use the *#code# and **code*number# format and are sent as one block to GSM networks worldwide (you press the call button and get an on-screen reply). North-American star codes are the *XX vertical service codes (*67, *69, *72) used on US/Canadian landline, cable-VoIP, and CDMA lines. If you're on AT&T, T-Mobile, or a carrier outside North America, you're mostly using USSD codes.

*#06# instantly displays your phone's IMEI — its unique 15-digit hardware ID. It's the most universal phone code there is: it works on every GSM phone and iPhone, even with no SIM card and no service. You need the IMEI to report a phone lost or stolen, to check it before buying used, or to unlock it.

How do I check if my calls are being forwarded?

Dial *#21# and press call to see whether “forward all calls” is active and the number it's forwarding to. *#61# checks no-answer forwarding, *#67# checks busy forwarding, and *#62# checks forwarding when your phone is off or unreachable. To turn everything off at once, dial ##002#.

Do USSD codes work on iPhone and Android?

Yes — the standard GSM codes (*#06#, *#21#, **21*number#, #31#, and so on) work the same on both, because they're carrier commands, not app features. A few diagnostic codes are platform-specific: *#*#4636#*#* opens an Android testing menu, and *3001#12345#* opens iPhone Field Test mode. Always press the green call button, not enter.

Are any USSD codes dangerous?

Some are. Certain manufacturer “reset” or “format” USSD codes wipe your phone instantly with no confirmation prompt, and a malicious link can auto-dial one. We deliberately leave those off this list. Rule of thumb: never dial a USSD code you found in a random message or pop-up, and never one described as a “reset,” “format,” or “wipe” unless you're following your manufacturer's official instructions and have a backup.

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USSD code list

Search every common GSM USSD code — *#06#, *#21#, ##002# and more — and see what each one means in plain English. Works on Android, iPhone, and most GSM carriers worldwide.

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24 USSD codes

*#06#Show IMEIUniversal GSMDisplays your phone's unique IMEI (and serial) number.
The single most universal phone code — it works on every GSM phone (and iPhones), even with no SIM card inserted and no service. It pops your IMEI on screen instantly. You need the IMEI to report a phone lost or stolen, to check it against a blacklist before buying used, or to unlock it with a carrier.
*#07#Show SAR / radiation infoUniversal GSMShows the device's regulatory SAR (radiation exposure) data.
On many modern Android phones and iPhones this opens the regulatory / SAR information screen, listing the Specific Absorption Rate measured for the device. Availability and the exact screen vary by manufacturer and region.
**04*<old>*<new>*<new>#Change SIM PINUniversal GSMChanges the PIN that locks your SIM card.
Replace <old> with your current SIM PIN and <new> with the new PIN twice, then press call (for example **04*0000*1357*1357#). This changes the SIM's lock code, not your voicemail or screen-lock PIN. SIM PIN must already be enabled in your phone's settings for this to work.
**05*<PUK>*<new>*<new>#Unblock SIM with PUKUniversal GSMResets a PIN-locked SIM using the carrier's PUK.
If you entered the wrong SIM PIN too many times and the SIM is blocked, dial this with your PUK (Personal Unblocking Key, from your carrier or the SIM card holder) and a new PIN twice. Warning: entering the wrong PUK 10 times permanently disables the SIM and you'll need a replacement.
*#5005*7672#Show SMS center numberUniversal GSMDisplays your message center (SMSC) number.
Returns the SMS service-center number your phone uses to send texts. Useful for troubleshooting when texts won't send — a wrong or missing SMSC is a common cause. Works on iPhone and most GSM Androids.
*#21#Check 'forward all calls' statusUniversal GSMShows whether all incoming calls are being forwarded, and where.
An interrogation code — it doesn't change anything, it just reports back. Dial it to see if unconditional call forwarding is active and the number calls are going to. The go-to check when callers say they can't reach you or your calls vanish silently.
*#61#Check 'forward when no answer' statusUniversal GSMReports your no-answer forwarding setting.
Shows whether calls forward when you don't pick up within the ring timeout, and to which number. Pairs with the **61* activation code.
*#62#Check 'forward when unreachable' statusUniversal GSMReports forwarding for when your phone is off / out of service.
Shows the number calls divert to when your phone is switched off, in airplane mode, or has no signal — often your voicemail by default. Pairs with the **62* activation code.
*#67#Check 'forward when busy' statusUniversal GSMReports your busy-line forwarding setting.
Shows where calls go when your line is already busy, and whether the divert is active. Pairs with the **67* activation code.
**21*<number>#Forward all callsUniversal GSMDiverts every incoming call to <number>.
The GSM equivalent of the *72 star code. Dial **21*, the destination number, then # and press call — the network confirms with a text. Used by AT&T, T-Mobile, Rogers and most GSM carriers. For a filled-in code by carrier, use the call-forwarding code generator.
**61*<number>#Forward when no answerUniversal GSMDiverts calls you don't answer in time to <number>.
Forwards a call only when you don't pick up within the ring timeout. The GSM equivalent of the *71 conditional star code — the setup most small businesses want so they answer when free and an answering service catches the rest.
##002#Cancel ALL forwardingUniversal GSMTurns off every type of call forwarding at once.
The master reset for diverts — clears unconditional, busy, no-answer, and unreachable forwarding in one command. The fastest fix when your calls are mysteriously going elsewhere and you're not sure which rule set it. Press call after dialing.
##21#Cancel 'forward all calls'Universal GSMTurns off unconditional forwarding only.
Cancels just the **21* forward-all rule, leaving any conditional (busy / no-answer) diverts in place. The GSM equivalent of the *73 cancel star code.
*#31#Check caller-ID (outgoing) statusUniversal GSMShows whether your number is hidden on outgoing calls.
Reports your CLIR (Calling Line Identification Restriction) setting — i.e. whether the people you call can see your number. An interrogation code; it changes nothing.
#31#Hide my number (all calls)Universal GSMPermanently withholds your caller ID on outgoing calls.
Turns on persistent caller-ID blocking so every call you make goes out private — the GSM way to do what *67 does per-call. Reverse it with *31#. To hide your number for just one call, dial #31# immediately before that number.
*31#Show my number (all calls)Universal GSMTurns off persistent caller-ID blocking.
Re-enables showing your caller ID on outgoing calls after you'd hidden it with #31#.
*#30#Check incoming caller-ID statusUniversal GSMShows whether you can see who's calling you.
Reports your CLIP (Calling Line Identification Presentation) setting — whether incoming caller IDs are delivered to your phone. If callers show as “Unknown,” checking this can confirm the feature is active on your line.
*#43#Check call-waiting statusUniversal GSMReports whether call waiting is on.
Tells you if call waiting (the beep that lets a second caller in while you're on a call) is currently enabled on your line.
*43#Turn call waiting onUniversal GSMEnables the call-waiting feature.
Activates call waiting so a second incoming call beeps in while you're already on a call, letting you switch between them.
#43#Turn call waiting offUniversal GSMDisables call waiting entirely.
Turns call waiting off so a second caller goes straight to voicemail (or your forwarding rule) instead of interrupting your current call. Unlike *70, which is per-call, this is a persistent setting.
*#33#Check call-barring statusUniversal GSMReports whether outgoing calls are barred.
Shows your call-barring (outgoing call restriction) status. Call barring is carrier-controlled and protected by a barring password that's separate from your SIM PIN — set or obtained from your carrier.
*33*<pin>#Bar all outgoing callsUniversal GSMBlocks all outgoing calls (needs barring password).
Restricts the line from placing outgoing calls, using your network barring password as <pin> (not your SIM PIN — get it from your carrier; the default is often 0000 or 1234 but varies). Cancel with #33*<pin>#. Behavior and availability depend on the carrier.
*#*#4636#*#*Android info & testing menuAndroidOpens hidden phone, battery, and usage diagnostics on Android.
Type it into the Android dialer to open a “Testing” menu with phone information (signal, network type, ping), battery details, and usage statistics. Read-only on most builds, but don't change radio-band settings unless you know what you're doing. Hidden or removed on some manufacturer skins.
*3001#12345#*iPhone Field Test modeiPhoneShows precise iPhone signal strength in dBm.
Dial it on an iPhone and press call to open Field Test mode, which reports your real signal strength as a dBm number (closer to 0 is stronger; -50 is excellent, -120 is nearly no signal) — far more accurate than the dots. Useful for finding the best spot for reception.

One safety rule

Never dial a USSD code from a random text, pop-up, or website — especially one called a “reset,” “format,” or “wipe.” A few manufacturer codes erase a phone instantly with no confirmation. We deliberately leave those off this list. Every code above is safe and read-only or reversible.

What is a USSD code?

USSD stands for Unstructured Supplementary Service Data. A USSD code is a short string you type into your phone's dialer — something like *#06# or **21*5551234#— that gets sent to your carrier's network as a single command. The network runs it and replies right on your screen, usually within a second or two.

Unlike a normal phone number, a USSD code is interactive and real-time. The format tells you what it does: codes wrapped in *#…# are usually interrogation codes that just check a setting; **…# codes activate a feature; and ##…# codes cancel one. Always press the green call button after typing — not enter — so the phone treats it as a network command.

USSD codes are a GSM-network standard, so they work the same across most carriers and countries. North-American landline and cable-VoIP lines use star codes (the *67 / *72 family) for many of the same jobs.

The most-used USSD codes

The handful worth memorizing. Use the searchable tool above for the full list, including caller-ID, call-waiting, and SIM codes.

Code	What it does
*#06#	Show IMEI. Displays your phone's unique IMEI (and serial) number.
#50057672#	Show SMS center number. Displays your message center (SMSC) number.
*#21#	Check 'forward all calls' status. Shows whether all incoming calls are being forwarded, and where.
*21<number>#	Forward all calls. Diverts every incoming call to <number>.
##002#	Cancel ALL forwarding. Turns off every type of call forwarding at once.
#31#	Hide my number (all calls). Permanently withholds your caller ID on outgoing calls.

Replace <number> with your destination phone number (digits only). For a filled-in forwarding code by carrier, use the call forwarding code generator.

USSD code FAQ

What is a USSD code?+
USSD (Unstructured Supplementary Service Data) codes are short strings — like *#06# or **21*number# — that you type into your phone's dialer and send to the carrier's network as a command. The network runs it and replies on screen, usually instantly. They control device and account features: checking your IMEI, turning call forwarding on or off, hiding your caller ID, and more. They're the GSM cousins of North-American star codes.
What's the difference between a USSD code and a star code?+
Both start with symbols and control phone features, but they're different families. USSD / MMI codes use the *#code# and **code*number# format and are sent as one block to GSM networks worldwide (you press the call button and get an on-screen reply). North-American star codes are the *XX vertical service codes (*67, *69, *72) used on US/Canadian landline, cable-VoIP, and CDMA lines. If you're on AT&T, T-Mobile, or a carrier outside North America, you're mostly using USSD codes.
What does *#06# do?+
*#06# instantly displays your phone's IMEI — its unique 15-digit hardware ID. It's the most universal phone code there is: it works on every GSM phone and iPhone, even with no SIM card and no service. You need the IMEI to report a phone lost or stolen, to check it before buying used, or to unlock it.
How do I check if my calls are being forwarded?+
Dial *#21# and press call to see whether “forward all calls” is active and the number it's forwarding to. *#61# checks no-answer forwarding, *#67# checks busy forwarding, and *#62# checks forwarding when your phone is off or unreachable. To turn everything off at once, dial ##002#.
Do USSD codes work on iPhone and Android?+
Yes — the standard GSM codes (*#06#, *#21#, **21*number#, #31#, and so on) work the same on both, because they're carrier commands, not app features. A few diagnostic codes are platform-specific: *#*#4636#*#* opens an Android testing menu, and *3001#12345#* opens iPhone Field Test mode. Always press the green call button, not enter.
Are any USSD codes dangerous?+
Some are. Certain manufacturer “reset” or “format” USSD codes wipe your phone instantly with no confirmation prompt, and a malicious link can auto-dial one. We deliberately leave those off this list. Rule of thumb: never dial a USSD code you found in a random message or pop-up, and never one described as a “reset,” “format,” or “wipe” unless you're following your manufacturer's official instructions and have a backup.

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