# \[Hilo\] Why many AT commands return ERROR?

**URL:** <https://forum.sierrawireless.com/t/hilo-why-many-at-commands-return-error/6503>\
**Category:** HL Series FAQ\
**Created:** [July 19, 2013, 6:36am UTC](https://forum.sierrawireless.com/t/hilo-why-many-at-commands-return-error/6503 "2013-07-19T06:36:20Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![FAQ\_Poster](https://avatars.discourse-cdn.com/v4/letter/f/f9ae1b/32.png) [@FAQ\_Poster](https://forum.sierrawireless.com/u/FAQ_Poster)\
**Post date:** [July 19, 2013, 6:36am UTC](https://forum.sierrawireless.com/t/hilo-why-many-at-commands-return-error/6503/1 "2013-07-19T06:36:20Z")

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[Hilo] Why many AT commands return ERROR?  
Answer: Please check if SIM card is inserted correctly, and check if the PIN code is needed  
Also please set \<AT+CMEE=2\> to know more details of the ERROR code.