Disable PIN on Huawei E1550

I prepared a 3G Router with failover to the 3G WAN via USB Stick in case the main DSL Uplink fails. The router has no option to pass a PIN to the available Huawei E1550, even though the mode is supported in general.

Since I wanted to disable the PIN constraints using standard Linux tools I gathered some information about the AT command set of the Huawei E1550 resp. E169 and it was straightforward, once you know the command syntax:

  • First connect minicom to /dev/ttyUSB0 (Bps/Par/Bits=115200 8N1 and Hardware Flow Control will work fine). The device name may vary, depending on connected USB devices or reconnect events.
  • You can get useful information including the IMEI using ATI.
  • The following command will disable the PIN (replace XXXX by the preconfigured PIN): AT+CLCK="SC",0,"XXXX"
  • Exit minicom, unplug the stick, replug, check /dev/ttyUSB* and call minicom again.
  • Check for a 0 in the output of the following command: AT+CLCK="SC",2

Don’t try that more than a second time on failure, otherwise you need to fallback to the PUK.

Even if you don’t need the following commands to disable the PIN, I consider them extremely helpful:

  • List available command: AT&V
  • Enable PIN: *AT+CLCK="SC",1,"XXXX"
  • Pass the PIN: AT+CPIN="XXXX"
  • Status of PIN Setting: AT+CPIN?
    • READY is fine.
    • SIM PIN is waiting for the PIN entry by AT+CPIN=XXXX
    • SIM PUK is waiting for the PUK entry, in this case the PIN is not enough.