Just thought I’d take a second to list out some cool codes you can use on your Apple iPhone to get an inside look at what’s going on with the phone.
Most notable is the “Field Test Mode” *3001#12345#*. Just type this in your phone screen and press call. You will be taken to the field test mode of the iPhone where you can see specifics like signal strength, associated tower, dBm and other antenna signal specific technical stuff. To exit this mode, simply press the home button. As a note, this code won’t work with IOS 4.0. You need the Apple IOS 4.1 or greater. For some reason, Apple deprecated the “field test” code in version 4.0.
Another interesting is *#21# which gives you instant access to call handling settings for inbound calls. This mode displays settings for inbound calls, inbound faxes (yep), and multiple other varians of inbound call handling.
This barely interesting code, *#06# allows you to view your IMEI, essentially your phones network serial number given by Apple. This is useful if you enjoy viewing useless information.
In general, the *# prefix on command codes will “interrogate” the phone, ** prefix is used to “setup” the phone and ## is used to delete or terminate instructions.
I have about 30 more codes currently being verified. I’ll post them when we’re sure they are accurate. Most of the codes mentioned here are ATT codes, but I’m working on a handful of apple specific codes that look promising. More to come.