From Tmplab

Work in Progress

Yet another introduction to understand basically how GSM network works by experiencing them. This wiki uses an USB 3G modem.


  • Here a Huawei 1750 is used, many other should works.
  • Serial port connection. It should bring 3 things in /dev, like ttyUSB0, ttyUSB1 and ttyUSB2 in Linux. Use it 8n1 9600 bauds, DTR/RTS ON on startup
  • Terminal software :

Linux : use picocom : picocom --echo /dev/ttyUSB2

OS X: i.e coolterm. Use tty.HUAWEIMobile-Pcui among the 3 serial ports tty.HUAWEIMobile-Diag, tty.HUAWEIMobile-Modem, tty.HUAWEIMobile-Pcui

AT commands

  • Get sure it's working type :


Manufacturer: huawei
Model: E1750
Revision: 11.XXXXXXXX

  • To enter a pin code (i.e 0000). If a pin authentication is required do it, it's needed to use other commands like network interactions.


  • AT+COPS? display the connected network, name and some infos

+COPS: 0,0,"F SFR",2

  • AT+COPS=? Displays all available networks

+COPS: (3,"F-Bouygues Telec","BYTEL","20820",2),(3,"Orange F","Orange","20801",2),(2,"F SFR","SFR","20810",2),(3,"","","20815",2),,(0,1,2,3,4),(0,1,2)

  • AT+CREG displays other informations on the connected network.

AT+CREG=2 Asks for advanced informations

+CREG: 5, 55002A, 2ED3

552A = 21802 = Location area number

2ED3 = 11987 = network cell ID

Try also


+CREG: 2,5, 55002A,2ED3

2ED3 is the local network cell ID

  • AT+CSQ Displays the radio quality

+CSQ: 10,99


  • You may ask what happend if your have no available network around you (or if you're jammed ?)

MODE Command will probably display no service 0 and no submode 0 : ^MODE:0,0
AT+COPS? may answer 0 : +COPS: 0
A service state change indication can also be displayed : ^SRVST:0

  • And when I got a network back online ?

Pretty much the same, you'll have service change ^SRVST, a new mode and obviously a new operator recognized with COPS command

  • Are all networks around me legit ?

You may look at your GPS position, lookup for known networks at and compare. You can contribute to this project by exploring your environment.

More ?