Advanced GPRS Modem Usage

From Peter Nixon's knowledgebase

While they may seem to be an exotic breed, Internal and External GPRS modems, 3G/GPRS Mobile Connect Cards and 3G/GPRS capable mobile phones all use a special GPRS subset of the standard AT command set which means that they can be used from any device and operating system that supports a "normal" modem. This means you can happily dial up to GPRS from your Windows, Linux, Apple Mac, or BSD system, or even a Cisco router for that matter all without loading any special "GPRS Connect" software.

Contents 1 Dial your GPRS Modem with AT Commands 1.1 Define CID profiles 1.1.1 Define the default Profile 1.1.1.1 Windows 1.1.1.2 SUSE Linux 1.1.2 Define a Numbered Profile 1.2 Dial CID Profile 2 Other Usefull GPRS Modem Commands 2.1 Getting Information 2.1.1 Device Information 2.1.2 List CID profiles 2.1.3 List CID range 2.2 PIN Security 2.2.1 Enter PIN 2.2.2 Disable PIN 2.3 Hardware and Network Control 2.3.1 GPRS modem control 2.3.2 GSM registration 3 Tested Devices 4 Operator Specific Info 4.1 Telstra 4.2 Turkcell 4.3 Vodafone Turkey 5 External Links

Dial your GPRS Modem with AT Commands

Using a GPRS modem without any special software requires first defining a GPRS (CID) profile which at a minimum lists the APN you will connect to, and then as a second step, using that profile to "dial up" to GPRS. The number of CID profiles supported varies between vendors and device models. Be aware that most Nokia telephones, support only one profile, so trying to set or dial any other profile number will give an AT command ERROR.

Define CID profiles

Define the default Profile

To (re)define the default GPRS connection profile on a device as an IP connection to the internet APN you can simply use the command:

AT+CGDCONT=,"IP","internet"

If you are setting up a computer and wish it to work with any GPRS modem/telephone without configuring each device manually, you may put this command in the modem's Initialisation string so whatever device you connect it is (re)configured every time you dial.

Windows

Control Panel -> Phone&Modem Options -> Modems -> Properties -> Advanced -> Extra Initialisation Commands

SUSE Linux

YaST Control Center -> Network Devices -> Modem -> Edit -> Details -> Init 1

Define a Numbered Profile

If you have a device which supports more than one profile, you may individually define each profile by specifying the profile number as part of the command. To define profile #1 as an IP connection to the internet APN use:

AT+CGDCONT=1,"IP","internet"

Dial CID Profile

You may dial the default profile with the command:

ATD*99#

On a PC (Windows, Linux etc) you will not need to put the leading "ATD" so the following is enough:

*99#

Alternatively you may specifically dial profile #1 with:

ATD*99***1#

Other Usefull GPRS Modem Commands

Getting Information

There are a number of usefull commands for querying your device for it hardware and configuration information

Device Information

You may list the device information of any modem (not just GPRS modems) with:

ATI

You should see a response from the device something like:

Manufacturer: HUAWEI TECHNOLOGIES CO., LTD.
Model: 183
Revision: I:12.16.01G
IMEI: 356570000000001
+GCAP: +CGSM,+FCLASS,+DS

Some modems are much less verbose though and need to be prodded a little more to learn about them. Below is the output from the inbuilt 3G modem in many Toshiba notebooks:

ati
F3507g
OK

ati1
R1B/1
OK

ati2
OK

ati3
Ericsson
OK

ati4
OK

ati5
Configuration Settings on Channel 2
&C: 1
&D: 2
*EIAC: 1,1,"Ericsson"
*ELIN: 1
ERROR

ati6
OK

ati7
PC Card Configuration Profile
Product Type       PCI Express Mini Card
Interfaces         USB
OK

ati8
OK

ati9
(0136ERI130B\\MODEM\\F3507g2F)

List CID profiles

List currently configured GPRS Profiles (You may of course do this from your telephone menu also)

AT+CGDCONT?

You should see a response from the device something like:

+CGDCONT: 1,"IP","internet","",0,0
+CGDCONT: 2,"IP","suntel","",0,0

This response means that the device currently has 2 CID profiles configured. Both are IP profiles. Profile #1 connects to the internet APN and profile #2 connects the the suntel APN.

List CID range

List CID profile range

AT+CGDCONT=?

You should get a reply like:

+CGDCONT: (1-16),"IP",,,(0-1),(0-1)
+CGDCONT: (1-16),"PPP",,,(0-1),(0-1)

This respone means that the device supports a maximum of 16 possible CID profiles of either IP or PPP type.

PIN Security

When you receive a new SIM card from your operator it will often have PIN security enabled.

Enter PIN

If your SIM card has PIN security enabled, you unlock the PIN with for the current session by sending the following command (Where xxxx is your current PIN):

AT+CPIN="xxxx"

You will need to put this in as one of the modem initialisation strings if you plan on leaving PIN security enabled on the SIM.

Disable PIN

If your SIM card has PIN security enabled, you may disable it from asking for the PIN (Where xxxx is your current PIN):

AT+CLCK="SC",0,"xxxx"

You may of course do this in the normal way from your telephone menu also.

Hardware and Network Control

The following commands should not be required by most devices, but give additional control over lower level functions of the hardware.

GPRS modem control

Turn on the GPRS modem:

AT+CFUN=1

GSM registration

Start the GSM registration process:

AT+CGREG=1

Tested Devices

The following GPRS capable devices have been tested with SUSE Linux and the above instructions:

• Ericsson F3507g 3G Modem (Built into a Toshiba Portege A600 Notebook)
• Huawei Mobile Connect Model E618
• Nokia E61i smart phone (Serial Cable and Bluetooth)
• Siemens MC35 External GPRS modem
• Siemens MC45 External GPRS modem
• Sony Ericsson T68i telephone (Serial Cable and Bluetooth)
• Sony Ericsson T610 telephone (Serial Cable and Bluetooth)
• Sony Ericsson K600i telephone (Serial Cable and Bluetooth)
• Teltonika ModemPCI TMP-10x GPRS modem (Uses a Nokia Chipset)
• Turkcell VINN 3G USB Adaptor (Sold in Turkey)
• Vodafone Mobile Connect 3G/GPRS data card (Sold in Turkey)

Operator Specific Info

If you have a private APN please ignore the following information. Please note that you may use a different profile number than the examples.

Telstra

Telstra uses the telstra.internet APN for internet access so your modem initialisation string should like something like:

AT+CGDCONT=1,"IP","telstra.internet",,0,0
ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

Telstra also seems to require the username 'guest' and password 'guest'

Turkcell

Turkcell uses the internet APN for internet access so your modem initialisation string should like something like:

AT+CGDCONT=2,"IP","internet"

Vodafone Turkey

Vodafone Turkey still uses the telsim APN for internet access as of July 2007 so your modem initialisation string should like something like:

AT+CGDCONT=2,"IP","telsim"

External Links

• LINUX GPRS HOWTO
• GPRS/UMTS Access on a Mac
• ETSI Telecom Standards (ETSI TR 127 007 applies to GPRS Modems)