I have really poor reception at my house (because of my house's construction) so sometimes just a few dots (on the top left of the phone) as indicators of signal strength isn't enough.
Here is how to enable a full numerical signal strenth display on iOS which is very handy to know if your chances of having a nice call are high.
- Open the Phone.app and tap on Keypad
- Type *3001#12345#* (stars and all) and then tap on Call
- As soon as you tap the Call button, the Field Test app will open. You’ll notice that instead of the standard reception dots in the upper left-hand corner of your screen, you’ve got a negative number indicating the decibels referenced to one milliwatt (dBm).
- While in Test Field app, hold down the Sleep/Turn Off button until the Slide to power off screen comes up. Now, instead of turning the phone off, release the Sleep/Turn Off button and hold the Home button for a couple of seconds until it will return you to the Home Screen.
- That’s it, now your signal will be displayed numerically. You can tap on it to switch between the numeric and dots display.
How to read the numeric display:
There’s a whole lot to say here, but let’s keep it simple:
- -50dBm: perfect reception
- anything greater than -100dBm: decent reception
- anything less than -110dBm: you pretty much have an expensive iPod Touch
***Edited to add labels***
