Every iPhone user relies on intuitive menus but did you know that your device holds hidden shortcuts? These are secret codes, special USSD (Unstructured Supplementary Service Data) or MMI dial codes that unlock diagnostics, network info, account settings, and more.
In this article, you’ll learn the most useful iPhone secret codes, how to use them safely, and what each one does whether you’re curious, troubleshooting, or just want to explore.
What Are iPhone Secret Codes?
Secret codes are special combinations you dial on your iPhone’s keypad (starting with * or #) to access hidden screens and functions within iOS and your mobile network. These codes follow the USSD protocol, widely used in GSM-based systems for diagnostic and service commands.
They work instantly, and some activate hidden menus or telephony features without needing internet or an app.
Essential iPhone Secret Codes
Here’s a curated list of powerful iPhone codes you can safely use:
- *#06# – Displays your device’s IMEI number instantly
- *3001#12345#* – Launches Field Test Mode, letting you view detailed signal metrics like dBm, serving cell ID, frequency bands, and network info.
- *#21#, *#61#, *#62#, *#67# – Shows whether call forwarding is active for busy, unanswered, or unreachable statuses.
- *#31# – Checks current caller ID status.
- #31#Number – Hides caller ID for a single outgoing call.
- *43#, #43#, *#43# – Manages or checks call-waiting status.
- *3370#, #3370# – Enables or disables Enhanced Full Rate (EFR) mode, improving call clarity in poor signal zones (may slightly reduce battery).
- ##002# – Disables all conditional call forwarding at once.
Field Test Mode: Unlock Detailed Signal Info
Dialing *3001#12345#* opens the iPhone’s Field Test Mode, a hidden diagnostic suite offering raw network details. You can view:
- Signal strength in dBm (e.g. −50 is excellent, below −100 is weak)
- Cell ID, band index, LTE/5G band types
- Neighboring cell data and carrier aggregation status
Older carriers and iOS versions show full menus, while newer devices sometimes offer limited info or buggy UI.
Reddit user notes: “On newer iPhones, the Field Test menu may load partiallyor crashespecially after iOS upgrades.”
Another user shared: “In iOS 16/17 Field Test Mode failed until I enabled the 24‑hour time format.”
Why Some Codes Might Fail
Not all secret codes work universally. Common reasons:
- Carrier restrictions: Many codes like forwarding or balance checks depend on your mobile provider; they can vary with AT&T, Verizon, T‑Mobile, or local carriers.
- iOS updates: Apple occasionally alters or disables certain diagnostic commands in new iOS versions. For example, Field Test Mode input sometimes stops working in iOS 16+.
- Hardware/IP differences: Early iPhones used different modems (Qualcomm vs Intel), which affected certain USSD behavior. Modern models are more standardized.
Use These Codes Safely
- Don’t dial codes you don’t understand, some can unintentionally block calls or change forwarding.
- When checking call forwarding or barring codes, avoid altering settings unless necessary.
- Avoid sharing your IMEI (*#06#) publiclyit’s a unique device identifier.
- If anything breaks, reset your network settings or revert changes individually.
Quick Reference Table
| Code | Function |
| *#06# | Show IMEI / Device ID |
| *3001#12345#* | Open Field Test Mode (signal monitoring) |
| *#21#, *#67#, *#61#, *#62# | Call forwarding checks |
| *#31# / #31#Number | Hide/show caller ID |
| *43# / #43# / *#43# | Call waiting status/control |
| *3370# / #3370# | Voice clarity toggle (EFR mode) |
| ##002# | Disable all call forwarding |
Final Takeaway: Why iPhone Secret Codes Still Matter
These codes are not hacksthey’re built-in telephony tools from GSM/USSD infrastructure. They give you insight or control that’s hidden beneath iOS menus. While most users may never need to use them, tech-savvy users, support staff, or curious owners will find them useful for troubleshooting, diagnostics, or even privacy checks.
FAQs
What are iPhone secret codes?
Do iPhone secret codes work on all models?
Most codes work across all GSM-based iPhones, but some features like Field Test Mode may vary depending on iOS version, carrier, and modem type (Intel vs Qualcomm).
Is it safe to use iPhone secret codes?
Yes, as long as you stick to commonly known diagnostic codes (like *#06# or *3001#12345#*). Avoid dialing unfamiliar codes that could change network behavior without your knowledge.
Why does *3001#12345#* sometimes not work?
On iOS 16 and later, Field Test Mode may crash or show limited information due to changes in Apple’s modem access permissions. Restarting the phone or enabling 24-hour time can sometimes fix this.
Can secret codes damage my iPhone?
No. These codes are built into the system and won’t harm your phone. However, changing forwarding or network settings without understanding them can cause call or message issues.
Are these codes unique to the iPhone?
Not exactly. Many codes come from GSM standards and also work on Android devices but their function may differ depending on the phone’s manufacturer and carrier.
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