this SIM5218 AT command manual - Cooking Hacks

SIM5218 Serial AT Command Set
Presence of item.
0 not present
1 present
Size of array.If is stored by array,the value of must be less than .
Size of item.The value is given in octets.Because the format of is hexadecimal,the
length of should be equal to *2.
The error codes.These error codes are followed:
-1 Error parameters
0 Not present
1 Busy(Request is queued)
2 Bad(unrecognizable) command
3 The NVM is full
4 Command failed,reason other than NVM was full
5 Not active
6 Bad parameter in command block
7 Parameter is write-protected and thus read only.
8 Item not valid for target
9 Free memory exhausted
10 Address is not a valid allocation.
Examples
AT+CNVR=
+CNVR: (0-7157),256
OK
AT+CNVR=110
+CNVR: 110,1,0,1
OK
AT+CNVR=110,0
+CNVR: 1,"00"
OK
10.20 AT+CDELTA Write delta package to FOTA partition
Description
The AT+CDELTA command can be used to write delta package to FOTA partition. After writing
successfully, it will set the flag for updating. When module resets and checks the flag, then it starts
to update firmware. The delta package is saved as a file in file system.
SIM5218_Serial _ATC_V1.36 224
5/15/2012