You can use it for many things, depending on mobile phone model.
Mobile phones with operating system Symbian are supported with gnapplet application installed in phone. But Symbian S60 3rd edition phones are not supported by gnapplet. But you can use basic function using generic AT model.
Your ~/.gnokiirc file will seem like this:
[global]
port = /dev/ttyACM0
model = AT
connection = serial
/dev/ttyACM0 is symbolic device file for USB port. This can vary on your system, in general, it should be in /dev/ttyACMN or /dev/ttyUSBN, where N is non-zero integer. You can find out it by issuing this command in the shell: dmesg | grep tty.
Succesfull test of gnokii connection with the pohne can seem this way:
ostry@elitebook:~$ gnokii --identify
GNOKII Version 0.6.27
IMEI :
Manufacturer : Nokia
Model : Nokia E00
Product name : Nokia E00
Revision : V ICPR82_09w24
Finally, you can send SMS from command line (Linux shell):
echo "This is a test message" | gnokii --sendsms +PHONENUMBER -r
It works!