Run modem and SIM annotated AT diagnostic tests
Use a serial terminal to connect to your modem and run each command. Record the outputs for support.Note: Some scans (e.g., network search) can take up to 3 minutes to complete.
| Command | Function | Sample response |
|---|---|---|
| AT | Attention; verifies command path | OK |
| ATI | Module number | SARA-U201-03B-00 |
| AT+CGMI | Manufacturer identity | u-blox |
| AT+CGMM | Manufacturer model identity | SARA-U201 |
| AT+CPIN? | SIM PIN state (Hologram SIMs do not require a PIN) | +CPIN: READY |
| AT+CCID | SIM ICCID (profile identifier) | +CCID: 894450… |
| AT+CRSM=176,28539,0,0,12 | Read FPLMN (forbidden networks) | +CRSM: 144,0,“FFFFFFFFFFFFFFFFFFFFFFFF” |
| AT+CFUN? | Module functionality | +CFUN: 1,0 |
| AT+CSQ | Signal quality | +CSQ: 22,4 |
| AT+CREG? | GSM/SMS registration | +CREG: 0,5 |
| AT+CGREG? | 3G registration | +CGREG: 0,5 |
| AT+CEREG? | LTE/EPS registration | +CEREG: 2,5,“MI9S”,“25SS404”,8 |
| AT+CGDCONT? | PDP context parameters (APN) | +CGDCONT: 1,“IP”,“hologram”,“0.0.0.0”,0,0 |
| AT+CGACT? | PDP context activation | +CGACT: 1,1 |
| AT+COPS? | Operator selection status | +COPS: 1,2,“310260”,2 |
| AT+COPS=? | Networks in reach (scan) | +COPS: (1,“AT&T”,“AT&T”,“310410”,2) |
Note: Prefer capturing raw terminal text output instead of screenshots.
Next steps
- If
AT+CSQis very low, relocate the device or improve the antenna. - If not registered (
+CREG/+CGREG/+CEREG), verify SIM activation and supported RAT/bands. - Ensure APN is set to
hologramand the active PDP context matches the APN line.