[SMS PDU mode, data format and length calculation]
When the SMS is sent, use the SMS PDU mode, data format and length calculation method:
UDL is UD byte length
Such as: 7bit data "Hello"
UDL = 05, ud = e8 32 9b fd 06
Another example: 16bit data "ABC"
UDL = 06, ud = 00 61 00 62 00 63
CSMS length, to remove the byte length after SCA
Such as: 00 11 00 07 81 21 43 56 F7 00 00 AA 05 E8 32 9B FD 06
Where SCA is 00, one byte
AT CSMS = 17
Edition: 07 91 94 71 01 67 00 00 11 00 07 81 21 43 65 F7 00 F6 aa 05 68 65 6C 6C 6F
SCA is 07 91 94 71 01 67 00 00 ( 491710760000), 8 bytes
AT CSMS = 17
There are three types of data format:
7bit, 8bit, 16bit.
Among them, 7bit adopts the GSM character set, 8bit uses the ASCII character set, and 16bit uses the Unicode character set.
The byte sequence adopts the network byte order.
