# *#31# on iPhone: Check Caller ID Setting URL: https://byshahid.com/blog/check-caller-id-setting-star-hash-31-iphone/ App: Secret Codes: IMEI & Carrier (https://apps.apple.com/us/app/secret-codes-imei-carrier/id6807154322) Author: Muhammad Shahid Updated: 2026-11-04 > *#31#: See whether your number is being sent with outgoing calls. Interrogates the GSM Calling Line Identification Restriction setting. The network replies telling you whether your caller ID is presented or withheld by default. This reads the standing setting for your line — not what any single call will do, since *67 and *82 override it per call. - **Code:** *#31# - **What it does:** See whether your number is being sent with outgoing calls. - **Published for:** AT&T and T-Mobile - **Type:** GSM networks See whether your number is being sent with outgoing calls. This page explains what `*#31#` 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 *#31# do? Interrogates the GSM Calling Line Identification Restriction setting. The network replies telling you whether your caller ID is presented or withheld by default. This reads the standing setting for your line — not what any single call will do, since *67 and *82 override it per call. ## How do I use *#31#? - Open the Phone app and tap Keypad. - Type *#31# 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 | GSM networks | | Good to know | GSM networks only. Verizon and UScellular customers should check My Verizon or their account instead. | _Screenshot: The Secret Codes detail screen shows the steps, the carriers and an Open in Phone button._ ## Related caller id codes - [*82[number]: Show Your Number For One Call](/blog/show-your-number-for-one-call-star-82-number-iphone/) - [#31#[number]: Hide Your Number (GSM Style)](/blog/what-is-31-code-iphone/) - [*67[number]: Hide Your Number For One Call](/blog/hide-your-number-for-one-call-star-67-number-iphone/) - [*31#[number]: Show Your Number (GSM Style)](/blog/show-your-number-gsm-style-star-31-hash-number-iphone/) - [*#30#: Check Incoming Caller ID Service](/blog/check-incoming-caller-id-service-star-hash-30-iphone/) - [*#76#: Check Connected Line Presentation](/blog/check-connected-line-presentation-star-hash-76-iphone/) See all [caller id codes](/blog/iphone-codes/caller-id/) 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 *#31# do on iPhone? See whether your number is being sent with outgoing calls. Interrogates the GSM Calling Line Identification Restriction setting. The network replies telling you whether your caller ID is presented or withheld by default. ### What else should I know about *#31#? This reads the standing setting for your line — not what any single call will do, since *67 and *82 override it per call. ### What are the steps for *#31#? 1. Open the Phone app and tap Keypad. 2. Type *#31# exactly as written. 3. Press the green Call button and wait for the result. ### Where do I use *#31#? On the keypad of the Phone app. ### Do I need to press Call after typing *#31#? Yes. Type it on the Phone keypad, then press the green Call button. ### Is *#31# 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 *#31# work on? It is published for AT&T and T-Mobile. GSM networks only. Verizon and UScellular customers should check My Verizon or their account instead. ### Does *#31# 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 *#31# 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 *#31# 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 *#31#? *82[number]: Show Your Number For One Call. Override a standing caller ID block for one call. ### What else is in this category? #31#[number]: Hide Your Number (GSM Style). The GSM per-call caller ID block. ## Sources - [3GPP TS 22.030: Man-Machine Interface of the phone](https://www.3gpp.org/dynareport/22030.htm) - [Apple Support: iPhone User Guide](https://support.apple.com/guide/iphone/welcome/ios)