Secret Codes guide
*#21#, ##21# and **21*: What These Call Forwarding Codes Mean on iPhone
By Muhammad Shahid Khan · · 5 min read
Quick answer
They are GSM codes for unconditional call forwarding (service code 21): *#21# checks whether all your calls are being forwarded, ##21# erases that forwarding, #21# pauses it, and **21*number# forwards every call to that number. Only dial **21* with a number you chose yourself, because scammers use it to steal calls.
Secret CodesDial codes, SIM & network test · Free on the App StoreDownload free →| *#21# | Check unconditional call forwarding status |
|---|---|
| ##21# | Erase unconditional forwarding and its number |
| #21# | Deactivate forwarding but keep the number stored |
| *21# | Reactivate a stored forwarding number |
| **21*number# | Forward all calls to that number |
| Phone tapping | *#21# cannot tell you if your phone is tapped |
Codes with 21 in them are some of the most searched on any phone, partly because of viral posts claiming that *#21# reveals whether your phone is tapped. It does not. What the 21 family really controls is call forwarding, and once you know the pattern you can read every one of these codes at a glance.
I build Secret Codes: IMEI & Carrier, a free iPhone app with 317 verified dial codes, and the screenshots in this guide come from it. If you would rather tap than memorise codes, get Secret Codes on the App Store.
What does 21 mean in a phone code?
In the GSM standard, every network service has a number. 21 means unconditional call forwarding: every incoming call goes to another number, and your phone never rings. The symbols in front tell the network what to do with that service:
| Prefix | Action | Example |
|---|---|---|
*# | Check status (interrogate) | *#21# |
** | Register a number and turn on | **21*number# |
* | Turn on (using a stored number) | *21# |
# | Turn off, but keep the stored number | #21# |
## | Erase the service and the number | ##21# |
The same prefixes work with 67 (busy), 61 (no answer) and 62 (unreachable). That is why *#21# and *#61# look so similar.
What does *#21# do?
*#21# asks your network whether unconditional forwarding is on. It changes nothing. On iPhone, open Phone > Keypad, type it and press Call. The reply lists each service, such as voice, data, fax and SMS, and says whether it is forwarded. If voice calls show "not forwarded" or "disabled", nobody is diverting all your calls.
If you see a number listed next to voice, every call is going there. If you do not recognise it, erase it with ##21# or ##002#, then change your carrier account PIN.
What is the difference between ##21# and #21#?
##21#erases unconditional forwarding and removes the stored number. This is what you want if someone else set it up.#21#deactivates it but keeps the number on file, so*21#can switch it back on later. Handy if you forward calls to your office every Friday.
To cancel every kind of forwarding at once, not just 21, use ##002#. See what ##002# does before you dial it, because it can also turn off voicemail.
What does **21* do?
**21* followed by a number and #, for example **21*447700900123#, forwards every call to that number. Your iPhone will not ring at all. Use the full international number to be safe.
The **21* scam. Someone calls or messages pretending to be your carrier, a courier or a delivery company and asks you to dial a code starting with **21* or **61* to "confirm your number" or "receive a parcel". The number in the code is theirs. From then on they receive your calls, including one-time passcodes your bank reads out by voice. Never dial a forwarding code with a number someone else gave you.
Can *#21# tell me if my phone is tapped?
No. This myth has circulated for years. *#21# only reports call forwarding stored on your network. Lawful interception happens inside the network and is never shown to the phone, and spyware on a phone does not change forwarding settings. What forwarding can reveal is a simpler attack: someone quietly diverting your calls. Checking *#21#, *#61#, *#62# and *#67# covers that. For the meanings of the conditional codes, see call forwarding codes for iPhone.
Do these codes work on every iPhone?
They work on GSM-based carriers, which covers most networks worldwide and AT&T and T-Mobile in the US. Verizon uses *72 to forward and *73 to cancel. If a code returns an error, your carrier may not support it on your plan. On many carriers you can also see forwarding in Settings > Apps > Phone > Call Forwarding.
How Secret Codes helps
- 317 verified iPhone codes, each checked against a carrier, Apple or the 3GPP standard. Android-only and retired codes are left out.
- Plain-English explanations of what every code does before you dial it.
- Open in Phone puts the code in Apple's dialler. Nothing is ever dialled for you.
- Built around your carrier: each code says whether your network publishes it.
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Frequently asked questions
What does *#21# do on iPhone?
It checks whether unconditional call forwarding is on. It only shows the status and changes nothing.
What does ##21# do?
It erases unconditional call forwarding and the stored forwarding number on GSM networks.
What is the difference between #21# and ##21#?
#21# turns forwarding off but keeps the number stored. ##21# erases both the forwarding and the number.
What does **21* mean?
**21*number# forwards all incoming calls to that number. Your phone will not ring.
Can *#21# tell if my phone is tapped?
No. It only shows call forwarding. Lawful interception and spyware are not visible through this code.
How do I read the *#21# reply?
It lists services such as voice, data and SMS. "Not forwarded" or "disabled" means nothing is forwarded. A number next to voice means all your calls go there.
How do I stop all my calls being forwarded?
Dial ##21# to erase unconditional forwarding, or ##002# to erase every type of forwarding.
Is it safe to dial *#21#?
Yes. It is a status check and changes nothing.
Why should I not dial **21* from a message?
If the number belongs to a scammer, all your calls, including bank verification calls, will go to them.
Does *#21# work on Verizon?
Usually not. Verizon uses its own codes: *72 to forward and *73 to cancel.
What does *#21# show if forwarding is on?
It shows the number calls are forwarded to, next to the services that are forwarded.
Does Secret Codes include the full 21 family?
Yes. It includes the status, on, off and erase codes for all four forwarding types, with notes on whether your carrier publishes them.
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