I have a application with the module Q2682RD and some times I receive the error CME ERROR 13. The SIM it’s in place, the modem it’s registered in the network and I read the phone numbers in the phone book of the SIM. The error appears randomly. I’m not using the starter kit from Sierra Wireless, but I’m using a self designed PCB with only 2 layers. Can this problem be caused by noise from the GSM line?