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Disable PIN on Huawei E1550 (UMTS Stick)

I want to setup a 3G router providing failover to 3G over an USB Stick in case the DSL uplink fails. But the router can't pass a PIN to my Huawei stick.

Since I want 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 really quite simple, once you now the right commands:

• I first connected my minicom to /dev/ttyUSB0 (Bps/Par/Bits=115200 8N1 and Hardware Flow Control will work fine).
• You can get some information including the IMEI using ATI.
• The following command will disable PIN constraints (replace XXXX by your PIN): AT+CLCK="SC",0,"XXXX"
• QA - unplug the stick, replug and call minicom again to check for a 0 in the following output: AT+CLCK="SC",2

Even if you don't need them to disable the PIN constraint, I consider the following commands also useful:

• AT&V
  List of available commands
• AT+CLCK="SC",1,"XXXX"
  Enable the PIN constraint.
• AT+CPIN="XXXX"
  Pass the PIN, especially useful, if PIN constraint is enabled.
• AT+CPIN?
  Status of PIN constraint: READY is fine, SIM PIN is waiting for the PIN, SIM PUK is waiting for the PUK - the PIN will not suffice.