PDU format is a series of 8 bit information. Each byte is represented by two hexadecimal letters (two letters = 8 bit of information). To represent the end of a number with an odd number of digits a 'F' is used to fill the byte in the hi part of the byte.

If you save an SMS in the memory and you recall it as PDU you'll obtain a string like this

0281F011FF0081000000xxaaaaa

This is the meaning of the resulting text:

AABBCCDDEEFFGGHHIILLMMnnnnnnnnnnn

AA: SC ADDRESS LENGTH
BB: SC ADDRESS TYPE
CC: SC ADDRESS
DD: MESSAGE TYPE INDICATOR
EE: MESSAGE REFERENCE
FF: DESTINATION ADDRESS LENGHT
GG: DESTINATION ADDRESS TYPE
HH: PROTOCOL IDENTIFIER
II: DATA CODING SCHEME
LL: VALID PERIOD
MM: Lenght of the text
nnnnn..:Text in hexadecimal format, each byte represent an ASCII value

To send a FLASH sms you have to change the DATA CODING SCHEME from 00 to F0 (this will send a class 0 SMS)

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