GSM decoding with Nokia 3310 phone

Gsmdecode is used to decode the gsm messages from the gammu trace log and a Nokia DCT3 mobile phone. Nokia used a simple remote logging facility for debugging their DCT3 firmwares remotely, but apparently forgot to remove this when going into production. So you can enable it back with a special software described below.

Hardware needed

• mobile phone Nokia 3310 (900/1800mhz) or 3390 (1900mhz)
•  F-BUS and M2BUS Auto switching cable

Software needed

In Linux (for instance Ubuntu) we need to install gammu (from console):

sudo apt-get install gammu
sudo apt-get install dialog

Then we need to setup gammu:

gammu-config

Sometimes gammu-config doesn't work correctly and switches model and connection, so we must edit ~/.gammurc file:

nano ~/.gammurc

File must have the following content:

[gammu]

port = /dev/ttyS0
model = 6110
connection = mbus
synchronizetime = yes
logfile = 
logformat = nothing
use_locking = yes
gammuloc = 

Then we create subdirectory for data files...

mkdir ~/GSM
cd ~/GSM

...and either download and install Wireshark 1.1.2 or later  http://www.wireshark.org

...or alternatively use gsmdecode; download source code of  gsmdecode-0.7bis.tar.gz (direct download here ), extract it and compile it:

cd gsmdecode-0.7bis/
sudo apt-get install gcc g++ cpp gpp make automake
./configure
make all

According to THC wiki, gsmdecode has:

• SIM Toolkit support
• Concatenated SMS supported (e.g. sms longer than 140 octets).
• Service request support (e.g. *#100# requests).
• Other layer 3 support (long (23+ octet) RR messages, ...)

Now we need file nhm5_587.txt which helps us decode trace types and save it to GSM subdirectory. File was found here:

•  arch.cihar.com in tar.gz datafile
• we need toopen datafile and find the following directory: /gammu–upstream–0–patch-29.patches/new-files-archive/gammu/depend/dct3trac/
• there is a file nhm5_587.txt, which needs to be saved into GSM subdirectory.

However, you cah simply download file here:

• nhm5_587.txt

How to connect the hardware

We need to open Nokia mobile phone, take out the battery, insert SIM card, insert battery into cable and then connect cable to the mobile phone.

The other part of the cable should be connected to computer (COM port - /dev/ttyS0), or we use USB to serial converter for instance USB-serial DB09 Aten (then we have emulated serial port under Linux - /dev/ttyUSB0).

Now we can switch on the mobile phone and start recording trace log.

cd ~/GSM
gammu --nokiadebug nhm5_587.txt v20-25,v18-19

wireshark ~/GSM/out.xml

~/GSM/gsmdecode-0.7bis/src/gsmdecode -x <~/GSM/out.xml

~/GSM/gsmdecode-0.7bis/src/gsmdecode -i <~/GSM/out.xml

~/GSM/gsmdecode-0.7bis/src/gsmdecode -x <~/GSM/out.xml | grep 7/odd | awk '{ print $5 }' | sort | uniq -c

~/GSM/gsmdecode-0.7bis/src/gsmdecode -x <out.xml | grep "Local Area Code" |  awk '{ print $3 }'