# **21*[number]# on iPhone: Turn On Call Forwarding URL: https://byshahid.com/blog/turn-on-call-forwarding-star-star-21-star-number-iphone/ App: Secret Codes: IMEI & Carrier (https://apps.apple.com/us/app/secret-codes-imei-carrier/id6807154322) Author: Muhammad Shahid Updated: 2026-11-04 > **21*[number]#: Forward every incoming call to another number. Registers and activates unconditional forwarding in one step. Enter the destination number in full — for a US number use the 10 digits, or 1 plus the 10 digits. Once active, your iPhone will not ring at all; every call goes straight to the number you entered. - **Code:** **21*[number]# - **What it does:** Forward every incoming call to another number. - **Published for:** AT&T and T-Mobile - **Type:** GSM networks Forward every incoming call to another number. This page explains what `**21*[number]#` does, how to use it on an iPhone and which carriers it applies to. I build **Secret Codes: IMEI & Carrier**, a free iPhone app with 317 checked codes and guides, including this one. If you would rather tap than memorise, [get Secret Codes on the App Store](https://apps.apple.com/us/app/secret-codes-imei-carrier/id6807154322). ## What does **21*[number]# do? Registers and activates unconditional forwarding in one step. Enter the destination number in full — for a US number use the 10 digits, or 1 plus the 10 digits. Once active, your iPhone will not ring at all; every call goes straight to the number you entered. **Important:** While unconditional forwarding is on you will not receive any calls on this iPhone, including calls you are expecting. Remember to switch it off with ##21#. ## How do I use **21*[number]#? - Open the Phone app and tap Keypad. - Type **21*[number]#, replacing [number] with the full phone number, including the area code. - Press the green Call button. ## Which carriers does this apply to? | Published for | AT&T and T-Mobile | | Type | GSM networks | | Good to know | GSM networks only. On Verizon and UScellular use *72 instead. | _Screenshot: The Secret Codes detail screen shows the steps, the carriers and an Open in Phone button._ ## Related call forwarding codes - [*#21#: Check Call Forwarding Status](/blog/what-does-star-hash-21-mean/) - [##21#: Turn Off Call Forwarding](/blog/turn-off-call-forwarding-hash-hash-21-iphone/) - [#21#: Pause Call Forwarding](/blog/pause-call-forwarding-hash-21-iphone/) - [*21#: Resume Call Forwarding](/blog/resume-call-forwarding-star-21-iphone/) - [*#61#: Check No-Answer Forwarding](/blog/check-no-answer-forwarding-star-hash-61-iphone/) - [**61*[number]#: Forward When You Don't Answer](/blog/forward-when-you-dont-answer-star-star-61-star-number-iphone/) See all [call forwarding codes](/blog/iphone-codes/call-forwarding/) or [every category of iPhone codes](/blog/iphone-codes/). ## How Secret Codes helps Secret Codes keeps this and every other entry a search away. Pick your carrier once and each entry says whether it is published for your line. You can save favourites, add a private note, and record whether a code worked on your line. **Secret Codes: IMEI & Carrier** is free on the App Store: https://apps.apple.com/us/app/secret-codes-imei-carrier/id6807154322 ## FAQ ### What does **21*[number]# do on iPhone? Forward every incoming call to another number. Registers and activates unconditional forwarding in one step. Enter the destination number in full — for a US number use the 10 digits, or 1 plus the 10 digits. ### What else should I know about **21*[number]#? Once active, your iPhone will not ring at all; every call goes straight to the number you entered. ### What are the steps for **21*[number]#? 1. Open the Phone app and tap Keypad. 2. Type **21*[number]#, replacing [number] with the full phone number, including the area code. 3. Press the green Call button. ### Where do I use **21*[number]#? On the keypad of the Phone app. ### How do I add the number to **21*[number]#? Replace [number] with the full phone number, including the area code, then press Call. ### Is **21*[number]# a hidden or secret code? No. It is a standard GSM code, handled by the network rather than by a hidden menu on the iPhone. ### Which carriers does **21*[number]# work on? It is published for AT&T and T-Mobile. GSM networks only. On Verizon and UScellular use *72 instead. ### Is there anything to watch out for with **21*[number]#? While unconditional forwarding is on you will not receive any calls on this iPhone, including calls you are expecting. Remember to switch it off with ##21#. ### Does **21*[number]# work on Android phones too? GSM codes are a network standard, so they generally behave the same on any phone on a network that supports them. ### Will **21*[number]# work outside the US? It depends on the network you are on. GSM codes are a standard, but each network decides which it supports. ### What if **21*[number]# does not work on my iPhone? Check that it applies to your carrier first, because carriers decide which services they offer and can change them. If it should apply to your line, contact your carrier. ### What is related to **21*[number]#? *#21#: Check Call Forwarding Status. See whether unconditional call forwarding is switched on. ## Sources - [3GPP TS 22.030: Man-Machine Interface of the phone](https://www.3gpp.org/dynareport/22030.htm) - [Verizon Support](https://www.verizon.com/support/)