Secret Codes guide

*#31# on iPhone: Check Caller ID Setting

By Muhammad Shahid · 4 November 2026 · 3 min read

Quick answer

*#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.

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Key facts
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.

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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.

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Frequently asked questions

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

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