The iPhone field mode shows a lot of information. In fact, it is more comprehensive than many other phone field modes, allowing you to see the details of the individual cell towers and a lot of detail about the cell phone network. For a phone that tries to hide much of the technical details of how it works, that’s a litte surprising. To access it, dial *3001#12345#*. If you are already in a call, just hit “add call”, enter the number above and hit call; the phone will go into test mode, but keep your call connected.
Main Screen
The first screen that you see is the main menu for the field mode. This presents you with the following choices: Network Information, Cell Information, GPRS Information, PDP information, Call Information and Versions. Let’s look at each of these in turn.
Network Information
The network information screen shows a large number of technical details on the cell phone network you are connected to. The particular things of interest for everyone are RX LevFull, which shows the received signal strength if you are in a call. TX Powr would seem to be the transmitting power, but it isn’t clear what that number means.
Cell Information
This is an interesting one: cell information shows the details of the cell phone towers that the iPhone can currently see. The items listed by each cell site are RX (the received signal stength), the FQ (frequency band), ST (station id), CI (the cell tower ID), N (the network ID) and # (a status code).
You can click on any of the listed cell towers to get more details, such as the network ID (here’s the one of an Italian carrier, and no, that’s definitely *not* I FOSK, lol), the cell ID (each tower has a unique ID) and the strength of the signal it is receiving from that tower. That’s wionderful, you can use this data to look at what cell towers are nearby and how strong the signal is! Can’t wait to try this in roaming mode and during GMS handovers!
GPRS Information
The GPRS information screen shows you various technical details of the state of the GPRS connection to the network.
PDP information
PDP is short for Packet Data Protocol, and refers to the way that the iPhone (and other phones) send Internet data over the cell phone network. This screen shows you the type of connection (which should always be IP), the name of the APM (Access Point Name) that your iPhone talks to on the GSM network, and the IP address of the iPhone.
Call Information
The Call information screen shows the details of the call that you are currently in, including the codec that it is using to compress your voice. On this example, we see that the iPhone is using the v3 AMR full-rate codec; there are several different codecs that can be used that use different amounts of bandwidth and offer various levels of voice quality.
Versions
This shows the basebans firmware version of the iPhone (note the misspelling of firmware: Apple aren’t perfect after all) and the LCD panel ID. This last one is interesting; it seems to be unique to each iPhone, and presumably identifies the individual touch panel. Why apple would do this isn’t clear, but they may want to track this information for quality control purposes.
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