- How to see your real signal strength (not just the bars)
- The quick way to check or disable call forwarding
- A one-call trick to hide your number instantly
Your iPhone’s Phone app isn’t just for making calls. Hidden beneath the keypad are a handful of secret dial codes that unlock network diagnostics and carrier-level settings you won’t find anywhere in the Settings app.
These so-called “interrogation codes” communicate directly with your mobile network via your SIM card. Most people will never need them – but when something isn’t working quite right, or you want deeper insight into your connection, they can be surprisingly useful.
Field Test mode
This is one of the most useful interrogation codes on iOS, to the point where we’ve previously devoted an entire article to it. Field Test mode provides a highly technical breakdown of your iPhone’s connection to your mobile network, which can be useful for pinpointing signal hotspots in your home. You get way more nuanced information than you would from just checking how many signal bars you have.
To enter Field Test mode, open the Phone app and dial *3001#12345#* on the keypad.
Call forwarding info
Want to find out if your phone is set up to forward calls to another number? This can can be a considerable security concern for some people. Dial these codes to bring up a readout of whether and where your phone forwards to another number under various circumstances:
To check Call Forwarding when a call goes unanswered, dial *#61#
To check Call Forwarding when you’re unreachable, dial *#62#
To check Call Forwarding when the call is busy or rejected, dial *#67#
To check if anything is being forwarded at all (calls, texts, SMS etc.), dial *#21#
Call waiting checks
You can manage call waiting – the process of notifying you that someone else is calling whilst being on another call – through Settings > Phone > Call Waiting, but it’s also possible to double-check with an interrogation code. If this feature isn’t working as expected, try this as a troubleshooting step before speaking to your carrier.
To check if call waiting is set up on your phone, dial *#43#. Then, you can dial *43# to enable call waiting, or #43# to disable call waiting.
Hide your identity
Its possible to set up Caller ID through iOS by going to Settings > Phone > Show My Caller ID. However, you can also check if Caller ID is active on your iPhone by dialling *#31#
There’s a genuinely useful spin-off from this, in that if you dial #31# immediately before a phone number, your call will be anonymous only for that specific call, meaning you don’t have to go in and flick any toggles on or off. Then there’s no chance you’ll forget to turn Caller ID back on.
