What is the iPhone Field Test code?

Dial *3001#12345#* and press call. This opens Field Test mode, which shows your real signal strength in dBm rather than the five dots in the status bar. Look for the RSRP value on LTE and 5G connections.

What secret codes work on iPhone?

Far fewer than on Android. The ones that work are *3001#12345#* for Field Test mode, *#06# for your IMEI, *#5005*7672# for the SMS center number, and the carrier codes for checking call forwarding (*#21#, *#61#) and caller ID (*#31#).

Why don't Android secret codes work on my iPhone?

The *#*#…#*#* format is an Android convention that iOS does not recognise, and *#0*# is Samsung-specific. Apple keeps its diagnostics inside iOS Settings rather than behind dialer codes, so most published iPhone code lists are recycled Android lists.

How do I check my iPhone signal strength in numbers?

Dial *3001#12345#* to open Field Test mode and read the RSRP value. Better than -90 dBm is strong, -90 to -105 is normal, -105 to -120 is weak, and below -120 is effectively unusable. The menu path changes between iOS versions.

Is there an iPhone code to see if my phone is tapped?

No. *#21# circulated as a hacking check but only reports call-diversion settings, and a result pointing at your carrier's voicemail is normal. No dialer code on any platform can detect spyware or surveillance.

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iPhone secret codes: Field Test mode and the codes that still work

iOS hides far less than Android, but a handful of dialer codes still work — including Field Test mode, which shows your real signal strength instead of the five dots.

iPhone has never had Android's sprawl of engineering codes. Apple keeps diagnostics inside iOS rather than behind dialer strings, so most lists claiming dozens of iPhone secret codes are recycling Android codes that do nothing on an iPhone. What does still work splits into two groups: one genuine Apple diagnostic, Field Test mode, and a set of network codes that are really carrier codes your iPhone passes through. Both are below.

Field Test mode — the real one

Dial *3001#12345#* and press call. This opens Field Test mode, Apple's built-in radio diagnostic.

What it gives you that the status bar does not is your actual signal strength in dBm rather than the five dots, which are a rounded approximation. Look for the RSRP value on an LTE or 5G connection.

Reading the number:

Better than -90 dBm is a strong signal
Between -90 and -105 dBm is normal
Between -105 and -120 dBm is weak, expect problems
Below -120 dBm is effectively unusable

The layout of Field Test changes between iOS versions and Apple has reorganised it more than once, so the exact menu path to RSRP moves around. It has never been removed, though, and the entry code has stayed the same for years.

Device codes that work on iPhone

Code	What it does
`*#06#`	Show IMEI and, on newer models, the eSIM EID
`#50057672#`	Show the SMS center number your texts route through
`*#07#`	Regulatory and SAR information, on some models and regions

*#06# is the most useful of these. It works with no SIM and no service, which makes it the standard way to check a used iPhone's IMEI against a stolen-device blacklist before you buy it.

*#5005*7672# is a genuine troubleshooting tool: if texts will not send, a wrong or missing SMS center number is a real cause, and this is how you read it.

Call forwarding and caller ID codes

These are carrier codes rather than Apple ones, so they work on iPhone but depend on your network supporting them:

Code	What it does
`*#21#`	Check whether calls are being forwarded
`*#61#`	Check the no-answer forwarding destination
`*#62#`	Check the unreachable destination
`##002#`	Cancel every forwarding rule at once
`*#31#`	Check whether your caller ID is hidden
`#31#<number>`	Hide your caller ID for one call

On iPhone you rarely need the forwarding codes, because iOS exposes the setting directly under Settings, Apps, Phone, Call Forwarding. The codes are still useful for the conditional rules — busy and no-answer forwarding — which the Settings screen does not show at all. How to forward calls on iPhone covers both routes.

The codes that do not work on iPhone

Most of what circulates as iPhone secret codes is Android codes in disguise. None of these do anything on an iPhone:

*#*#4636#*#* and every other code in the *#*#…#*#* format — that pattern is Android-only
*#0*# — a Samsung hardware test
Codes claiming to unlock a carrier-locked iPhone, which is an account-level request to the carrier and cannot be done from the dialer
Codes claiming to show who has been tracking or tapping your phone, which do not exist on any platform

On that last point: *#21# circulated widely as a phone-hacking check. It reports call-diversion settings only, and a result showing your carrier's voicemail as the destination is completely normal. What *#21# means and how to know if your phone is tapped go through what these codes can and cannot tell you.

FAQ

What is the iPhone Field Test code?: Dial *3001#12345#* and press call. This opens Field Test mode, which shows your real signal strength in dBm rather than the five dots in the status bar. Look for the RSRP value on LTE and 5G connections.
What secret codes work on iPhone?: Far fewer than on Android. The ones that work are *3001#12345#* for Field Test mode, *#06# for your IMEI, *#5005*7672# for the SMS center number, and the carrier codes for checking call forwarding (*#21#, *#61#) and caller ID (*#31#).
Why don't Android secret codes work on my iPhone?: The *#*#…#*#* format is an Android convention that iOS does not recognise, and *#0*# is Samsung-specific. Apple keeps its diagnostics inside iOS Settings rather than behind dialer codes, so most published iPhone code lists are recycled Android lists.
How do I check my iPhone signal strength in numbers?: Dial *3001#12345#* to open Field Test mode and read the RSRP value. Better than -90 dBm is strong, -90 to -105 is normal, -105 to -120 is weak, and below -120 is effectively unusable. The menu path changes between iOS versions.
Is there an iPhone code to see if my phone is tapped?: No. *#21# circulated as a hacking check but only reports call-diversion settings, and a result pointing at your carrier's voicemail is normal. No dialer code on any platform can detect spyware or surveillance.

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