Can anyone refer any URL for studying SMS in PDU format

Dear All,

GSM MODEM: SIM300 OR SIM900B
FROM : HYPERTERMINAL

I want to send/receive SMS in PDU mode (using concatenated SMS) in case of SMS text exceeds 160 characters. I can able to send Single SMS in PDU mode. Picture (Hyperterminal) attached. But, I failed to send Concatenated SMS. Picture (Hyperterminal) attached for this also. I think I have made a mistake in calculating Length field. Still I am little bit doubt in calculation on septets and octets. Any one can help to overcome this issue?

SINGLE SMS (Succeeded):
AT+CMGS=18
> 0011000C9119XXXXXXXXXX0000AA04D4E2940A

+CMGS: 29

OK

Concatenated SMS (Failed):

AT+CMGS=23

> 0041000C9119XXXXXXXXXX000004050003000301D4E2940A

00 -> USE STORED SMSC NUMBER
41 -> SMS SUBMIT WITH USER DATA HEADER PROVIDED
00 ->
0C -> PHONE NUMBER LENGTH
91 -> INTERNATIONAL PHONE NUMBER
19XXXXXXXXXX -> PHONE NUMBER
00 -> Protocol identifier
00 -> Data encoding scheme
04 -> USER DATA LENGTH (4 FOR STRING "TEST")
050003000301 -> USER DATA HEADER
0x05 -> USER DATA HEADER LENGTH
0x00 -> Information element identifier
0x03 -> Information element data length
0x00 -> A reference number
0x03 -> This message has 3 parts
0x01 -> This is part 2.

D4E2940A -> USER DATA ("TEST")


thanks

Try PDUspy maybe you will find that is useful.

this site may help u
https://www.developershome.com/sms/

I have done simple & concatenated SMS in PDU on SIM300 GSM Modem. Thanks to both of you.