A simple code can give you access to hidden information your iPhone, as well as allowing you to make changes to its private settings.
The iPhone’s Field Mode is a largely hidden but useful tool that allows you to see extra information about how your phone is connected to the internet.
The tool is enabled by dialling *3001#12345#* and then pressing the call button. Your phone will switch away onto a grey screen, after which you’ll see the extra information.
One of the most useful features is a more detailed signal strength indicator which should appear in the top-left hand corner.
Anything above -80 is roughly equivalent with full bars on the normal scale. Anything below -110 would be one or no bars and you are unlikely to be able to easily make a phone call.
In practise, the maximum strength ever achieved is around -40. No reception at all is around -120, though it goes all the way to -140.
If you want to keep that number in the corner, rather than the usual dots, then hold down the power button. The message to turn the phone off will appear, and then press the home button.
The feature should then be enabled. Users can switch between the two ways of viewing the signal by pressing on where they display, in the top-left hand corner.
There are a range of other codes that offer other information.
In pictures: iPhone 6s goes on sale
In pictures: iPhone 6s goes on sale
Despite the rain, some 40 on-line reservation buyers visit the Apple Store in Omotesando neighborhood as the iPhones new models - iPhone 6s and iPhone 6s Plus go on sale in Tokyo, Japan
Sam Shaikh holds up two bags containing the new iPhone as he is surrounded by store staff after the release and sale start of the new Apple IPhone 6S at the Apple store in Covent Garden, London
Apple fans pose for selfie at the store in Australia, during the launch of the new iPhone 6s
People cheer at the launch of the new iPhone 6s, at the store in Australia
19-years-old David Kiss from Debrecen, Hungary, shows off his new iPhone 6s at the Apple store in Munich, Germany. Kiss camped in front of the shop for almost a week to be the first to get the new smartphone
A customer tries out a rose gold iPhone 6s Plus smartphone at the Apple Store near the West Lake in Hangzhou city, Zhejiang province, China
A member of staff processes a transaction as customer purchase phones during the launch of the Apple iPhone 6s at The Apple Store Opera, in Paris, France
The Apple store in Beijing launches the new iPhone 6s
Veronika Babochkina, 27, from Moscow, Russia, looks at the new iPhone 6s at The Apple Store in Opera, after queuing for few days, in Paris
Jonathan Pierrard, 26, from Rossignol, Belgium is the first customer to leave with the new iPhone 6s at The Apple Store in Opera, after queuing for few days, in Parisr to open new shortcuts - a feature Apple calls 3D Touch. (AP Photo/Francois Mori)
Using *#33# will show the status of your call barring settings. That tool can be turned on and off using *33*pin# and #33&pin#. Swap PIN for your Sim PIN.
Using *#43# will tell you whether or not call waiting is turned on. That feature allows people to queue up when they ring you, so that the phone can alert you if someone is trying to get through while you’re already on a call.
It can be turned on using *43# and turned off again with #43#
*#06# will bring up your IMEI identifier number. That’s very useful because it can be used to shut down your phone remotely if it stolen, but it can also be accessed from the Settings app or on the phone’s box.Reuse content