PaulZC  
              
                  
                    August 22, 2024,  6:43am
                   
                  18 
               
             
            
              Hi @wenyuan  ,
By default, Echo is enabled on the 9603N modem. The modem echos back the AT command, then sends the response. You can disable the Echo by sending “ATE0”, and re-enable with “ATE1”. Is your code sending ATE0 ?
Please see:
  
  
    Hi Rick, 
OK - thanks. Can you please confirm that the boards you bought from us are https://www.sparkfun.com/products/13745  ? Assuming they are, then, yes, that is the Iridium 9602 modem. We have other products, including our own, which use the smaller 9603N modem. 
It does sound as if your modems are running newer firmware, and are possibly providing different responses. 
I can only find copies of the AT Command Reference dated 2014. Nothing newer than that. Nothing to indicate that the responses might have changed… 
Here is what I see with a 9603N modem dating from around 2017. I typed the AT+ commands into a terminal emulator, they are echoed back by the modem as I type. 
AT+CGMI 
Iridium 
OK 
AT+CGMM 
IRIDIUM 9600 Family SBD Transceiver 
OK 
AT+CGMR 
Call Processor Version: TA16005 
Modem DSP Version: 1.7 svn: 2358 
DBB Version: 0x0001 (ASIC) 
RFA Version: 0x0007 (SRFA2) 
NVM Version: KVS 
Hardware Version: BOOT07d2/9603NrevDE/04/RAW0c 
BOOT Version: TA16005 (rev exported) 
OK 
A…
   
 
I hope this helps,