iPhone GSM test mode

I google'd it when I needed to check some GSM radio network values when I'm home. It appeared out that iPhone has a "field test mode", which is enabled with *3001#12345#* code. You just need to type this and hit "Call". I wanted to save the number as a contact to "call" later, but when I call that contact it actually places a real GSM call for that number which is leading me to an announce for the failing call :)

When you do this, you reach to the main "Field Test" screen.

Notice the signal strength indication on top left of the screen. The unit for this number is dB as summarized here.

In the upper left hand corner, the 5 bars are replaced with a decimal indicating the power ratio in decibels (dB) of the measured power referenced to one milliwatt. These are measured on the negative side of zero so of course the closer you are towards a positive number, the stronger the ratio is and likewise a better chance of good service. Anything above a -85 is shows as 5 bars. Anything below -105 is zero bars and loss of connection usually occurs.

Here, I find "MM Info" and "GSM Cell Environment" items interesting.With the first one, I can see the serving network and LAC (Location Area Code).

"GSM Cell Environment" has details about the cells the phone is talking to. I could not find the serving cell ID with a quick check.

And it shows details of 6 possible neighboring cells.

The thing is when you're using 3G, it is not working properly. You can see the signal strength at the top left, but all you see is "Unknown" for all the fields.

I still could not find what I'm looking for, at iPhone's "field test" menu; but sure it looks useful and I'll dig it more :)

BTW, these images are taken on firmware 3.1.3 (7E18)