Your iPhone has a ‘secret menu’ that unlocks hidden features – here’s how to access it

A ‘secret menu’ hidden in Apple’s iPhone can only be accessed by entering codes using the digital keyboard.

The menu shows whether your calls are forwarded, how strong the signal strength really is, and a number to protect your smartphone – and more.

To access these features, type a series of numbers and symbols into your phone’s dialer as if you were about to dial a number.

To activate it, in most cases you have to press ‘call’, which will bring up a menu page).

The secret codes are based on Unstructured Supplementary Service Data (USSD), a communications protocol that allows devices to communicate with the network, and are typically used by technicians.

Invented in 1997, USSD delivers information to your phone (such as how much credit you have left) over the old-fashioned GSM network.

Known as “quick codes,” “function codes,” or “engineer codes,” these codes are usually specific to certain networks and devices (although some are nearly universal).

Here are some cool features you can unlock with codes on your iPhone.

Find out your TRUE signal strength

The bars your phone shows to indicate signal strength are often a pretty rough estimate, but with a code on your iPhone you can go into field test mode to check.

To do this, type *3001#12345#* into your phone’s dialer (it’s best to turn off Wi-Fi first)

From there you will see a lot of (very) technical data about your phone: under LTE RsrpRsrqSinr you can see information about your phone’s connection.

Under Rsrp you should be able to see the strength of your signal.

A level of -40 means a strong connection and -140 is a weaker one.

Hide your caller ID

To hide your caller ID when you call (so the person you’re calling can’t see who called them), you can type a USSD code for the number you want to call.

Just type *67 (in the US) to hide your number.

In Europe, try #31#.

This feature is dependent on your network allowing it (so it may not be available on certain networks or plans).

Find your IMEI number to protect your phone

Knowing your unique International Mobile Equipment Identity (IMEI) number can help your carrier block it if you lose your phone.

To see yours, just type *#06# – make a note of it, and if your handset is lost or stolen, contact your provider.

See if your calls are forwarded

You can check if your calls are forwarded (usually this is to your voicemail, but you can also check if someone has set up your calls to be forwarded elsewhere).

Type the USSD *#67# to see your forwarding settings.

Enable call barring

You can easily enable call barring (which blocks incoming calls) by entering a USSD.

Enter *#33# to check if call barring is enabled.

To enable this you will need your SIM PIN (if you don’t know it, contact your network provider)

Enter *33*SIM PIN# to enable call barring.

Enter #33*pin# to disable it.

Forward your calls to another phone

To forward your calls to another phone, simply enter a USSD code.

To do this, type in *21PHONENUMBER# and the phone will forward your calls (type the full phone number where it says PHONENUMBER.

This varies by network, so if you get an error, use *72 instead of *21.

Type *21# to turn it off.