For most users, the connection manager supplied with the USB modem is sufficient for getting connected and managing your modem. However, some users (especially those not using Windows computers) prefer to manage their modem directly, using AT commands. Here’s some useful commands for USB modems.

Selecting an APN
+CGDCONT=1,”IP”,”apn name”
e.g. for Vodafone UK – AT+CGDCONT=1,”IP”,”internet”

Querying signal strength
+CSQ
Returns two comma separated numbers. The first number is the signal strength (RSSI), the second number is unused. Here’s how to interpret RSSI:

0 <= -113dBm
1 -111dBm
2 – 30 -109dBm to -53dBm
31 >= -51dBm
99 Unknown

Setting operating mode
+CFUN=x

0 Low power mode
1 Online
4 Offline
6 Reset device
7 Turn off radio

Get manufacturer information
+CGMI

Get software version
+CGMR

Get SIM IMSI number
+CIMI

Get device IMEI
+CGSN

Get hardware version
^HWVER

Change PIN
+CPWD=SC,old pin, new pin

Enable PIN
+CLCK=SC,mode,pin

Mode: 0=unlock, 1=lock, 2=query state

Query system information
^SYSINFO
Returns: status, domain, roaming status, mode, SIM state

Status
0 No service.
1 Restricted service
2 Valid service
3 Restricted regional service.
4 Power-saving and deep sleep state

Domain
0 No service.
1 Only CS service
2 Only PS service
3 PS+CS service
4 CS and PS not registered, searching

Roaming
0 Non roaming state
1 Roaming state

Mode
0 No service.
1 AMPS mode (not in use currently)
2 CDMA mode (not in use currently)
3 GSM/GPRS mode
4 HDR mode
5 WCDMA mode
6 GPS mode

SIM state
0 Invalid USIM card state or pin code locked
1 Valid USIM card state
2 USIM is invalid in case of CS
3 USIM is invalid in case of PS
4 USIM is invalid in case of either CS or PS
255 USIM card is not existent,

Network selection
+COPS=? Return a list of networks
+COPS=mode, format, operator

Mode
0 Automatic
1 Manual
4 If manual fails, try automatic

Format
1 Long alpha
2 Short alpha
3 Numeric

Operator
Either the long alpha name, the short operator alpha code or the numeric code

Status
0 unknown
1 available
2 current
3 forbidden

System Config
^SYSCFG=mode, order, band, roaming, domain

Mode
2 Automatic search
13 2G ONLY
14 3G ONLY
16 No change

Order
0 Automatic search
1 2G first, then 3G
2 3G first, then 2G
3 No change

Band
80 GSM DCS systems
100 Extended GSM 900
200 Primary GSM 900
200000 GSM PCS
400000 WCDMA IMT 2000
3FFFFFFF Any band
40000000 No change of band

Roaming
0 Not supported
1 Roaming is supported
2 No change

Domain
0 CS_ONLY
1 PS_ONLY
2 CS_PS
3 ANY
4 No change