# *#331# on iPhone: Check International Call Barring URL: https://byshahid.com/blog/check-international-call-barring-star-hash-331-iphone/ App: Secret Codes: IMEI & Carrier (https://apps.apple.com/us/app/secret-codes-imei-carrier/id6807154322) Author: Muhammad Shahid Updated: 2026-11-04 > *#331#: Ask whether outgoing international calls are barred. An interrogation, so it changes nothing and needs no password. The network replies with the state of barring of outgoing international calls, usually broken down by basic service so you may see separate lines for voice, data, fax and SMS. - **Code:** *#331# - **What it does:** Ask whether outgoing international calls are barred. - **Published for:** AT&T and T-Mobile - **Type:** Support varies Ask whether outgoing international calls are barred. This page explains what `*#331#` 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 *#331# do? An interrogation, so it changes nothing and needs no password. The network replies with the state of barring of outgoing international calls, usually broken down by basic service so you may see separate lines for voice, data, fax and SMS. This is the single most useful string in the barring family because it is read only. If it answers at all, your line understands GSM barring and the activation strings are worth trying. If it errors, the rest of this family will error too. ## How do I use *#331#? - Open the Phone app and tap Keypad. - Type *#331# exactly as written. - Press the green Call button and wait for the result. ## Which carriers does this apply to? | Published for | AT&T and T-Mobile | | Type | Support varies | | Good to know | Read only and harmless to try. Many US lines answer with an error because barring was never provisioned, which tells you the whole family will be unavailable. | _Screenshot: The Secret Codes detail screen shows the steps, the carriers and an Open in Phone button._ ## Related call barring and sim pin codes - [#331*0000#: Cancel International Call Barring](/blog/cancel-international-call-barring-hash-331-star-0000-iphone/) - [*332*0000#: Bar International Calls Except Home](/blog/bar-international-calls-except-home-star-332-star-0000-iphone/) - [*331*0000#: Bar Outgoing International Calls](/blog/bar-outgoing-international-calls-star-331-star-0000-iphone/) - [#332*0000#: Cancel Except-Home Barring](/blog/cancel-except-home-barring-hash-332-star-0000-iphone/) - [#33*0000#: Cancel Outgoing Call Barring](/blog/cancel-outgoing-call-barring-hash-33-star-0000-iphone/) - [*#332#: Check Except-Home Barring](/blog/check-except-home-barring-star-hash-332-iphone/) See all [call barring and sim pin codes](/blog/iphone-codes/call-barring-and-sim/) 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 *#331# do on iPhone? Ask whether outgoing international calls are barred. An interrogation, so it changes nothing and needs no password. ### What else should I know about *#331#? The network replies with the state of barring of outgoing international calls, usually broken down by basic service so you may see separate lines for voice, data, fax and SMS. This is the single most useful string in the barring family because it is read only. ### What are the steps for *#331#? 1. Open the Phone app and tap Keypad. 2. Type *#331# exactly as written. 3. Press the green Call button and wait for the result. ### Where do I use *#331#? On the keypad of the Phone app. ### Do I need to press Call after typing *#331#? Yes. Type it on the Phone keypad, then press the green Call button. ### Is *#331# a hidden or secret code? No. It is a published service, not a hidden menu. iPhones do not have Android-style engineering menus. ### Which carriers does *#331# work on? It is published for AT&T and T-Mobile. Read only and harmless to try. Many US lines answer with an error because barring was never provisioned, which tells you the whole family will be unavailable. ### Does *#331# work on Android phones too? It is handled by the carrier or service rather than the iPhone, so it is not tied to one phone brand. Check with your carrier. ### Will *#331# work outside the US? It is published for US carriers and services, so do not count on it abroad. Ask your carrier before you travel. ### What if *#331# 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 *#331#? #331*0000#: Cancel International Call Barring. Allow international dialling again after *331*. ### What else is in this category? *332*0000#: Bar International Calls Except Home. While roaming, allow calls home but block all other international dialling. ## Sources - [3GPP TS 22.030: Man-Machine Interface of the phone](https://www.3gpp.org/dynareport/22030.htm)