Modem & SIM annotated diagnostic test

Note: Before you begin, please ensure your SIM is successfully activated in the Hologram Dashboard.

For instructions on sending AT commands to a device, click here. Keep in mind that the instructions are written for Hologram Novas but use basic serial communication and standard AT commands so the same commands can be used on all modems. If you are unable to open a serial communication channel with your modem, contact your original equipment manufacturer for instructions on sending AT commands to your device.

Modem, Module, & SIM Diagnostic Procedure

Using your favorite terminal program (Screen, Teraterm, Putty, GTKTerm, etc.), run the following commands and record their outputs. Copy this table and use the actual response field to paste your answers.

Note, the last command, below, may take up to 5 minutes to complete.

Command Function Sample Response Notes Actual Response 
AT Attention OK Determines if device can send commands  
ATI Module Number SARA-U201-03B-00 Device Type   
AT+CGMI Manufacturer Specific Identity u-blox Manufacturer  
AT+CGMM Manufacturer Specific Model Identity SARA-U201 Manufacturer Model Identity  
AT+GMM Manufacturer Specific Model Identity SARA-U201 Manufacturer Model Identity  
AT+CPIN? Check The SIM PIN +CPIN: READY Hologram SIMs do not require a SIM PIN   
AT+CCID Check The SIM ICCID +CCID: 1234567890123456789 ICCID is a unique SIM identifier  
AT+CRSM=176,28539,0,0,12 Read Data File 28539 In Binary Mode +CRSM: 144,0,"FFFFFFFFFFFFFFFFFFFFFFFF"

Forbidden or Restricted Network list

All F's indicate no Networks forbidden


AT+CFUN? Determine What Mode the Module Is In +CFUN: 1,0 Full functionality mode is needed  
AT+CSQ Signal Quality +CSQ: 22,4

Returns multiple values to indicate signal strength, use device command manual to decipher


AT+CREG? Network Registration Status +CREG: 0,5 GSM & SMS Network Registration  
AT+CGREG? GPRS Network Registration Status +CGREG: 0,5 3G Network Registration  
AT+CEREG? EPS Network Registration Status +CEREG: 2,5,"MI9S","25SS404",8 4G LTE Network Registration  
AT+CGDCONT? Read PDP Context Parameters (APN) +CGDCONT: 1,"IP","hologram","",0,0

APN should be hologram

Verify your device manual but generally AT+CGDCONT=1,"IP","hologram" will set APN


AT+CGACT? PDP Context Activation +CGACT:1,1 Indicates which PDP context is being used and if that PDP context is active.

The active context (1 in this example) should match the ext ID of the PDP context where the APN is set to hologram for connectivity

AT+COPS? Operator Selection Status and Current Operator +COPS: 1,2,"310260",2

Displays MCC + MNC of Network connected to. The last number is the RAT (Radio Access technology): 0 for GSM, 2/3 for 2G/3G, 7 for LTE, 8 for CAT-M1, 9 for Nb-IoT


AT+COPS=? Networks In Reach


If the module returns an error, please try again. This command can take up to 3 minutes to run.

Network Operators or Network MCC+MNC are displayed for available Networks and their associated Region



If you are not seeing the AT commands, you are typing try sending ATE.  If you prefer, you can run this script for the diagnostics to automatically execute.

Was this article helpful?
1 out of 2 found this helpful