# Thread: Problem in coding long SMS in 7 bit

1. ## Problem in coding long SMS in 7 bit

Why when coding long SMS in 7 bit the first octet shift left 1 time?

See the following example:
QRSTUVWXYZ coded in 7 bit concatenated will be
11050003030303A2D229B56ABD62B35A

Where
11- udl
05- udhl
00- IE
03- IEL
03- reference number
03 - total number of SMS
03 - 3/3 sms
A2D229B56ABD62B35A - UD
A2 - 1010 0010 (the regular 7 bit coding moved left by one bit &quot;0&quot and it's seems to be working in such way every time you send it. When trying to send the usual way it's not working (displays jibrish)

The following example shows this phenomenon
+CMT: ,28 ABCDEFG
07917952140227F244038599F939F1206091018194000E05000303030182C221B1683C02

+CMT: ,2 9 HIJKLMNOP
07917952140227F240038599F939F120609101810500100500030303029049E592D9743EA1

+CMT: ,30 QRSTUVWXYZ
07917952140227F244038599F939F12060910181150011050003030303A2D229B56ABD62B35A

By the way, found nothing about it in the specs. (03.40, 03.38)

2. ## RE: Problem in coding long SMS in 7 bit

Where
11- udl
05- udhl
00- IE
03- IEL
03- reference number
03 - total number of SMS
03 - 3/3 sms
Fill bits has to be added after header in order to get (7 bit)
septet boyndary says GSM spesification 03.40 before starting the actual 7 bit data. This is to avoid shifting. 8 seven bit characters can be put in 7 octets. There are phones which do not understand headers and they can still make sence of the message after the header too this way. So the first A2 is the last octet of the 7 octet
sequence and the coding should be according to that since the
user data header takes only 6 octets from the beginning of normal
user data.
A2D229B56ABD62B35A - UD
BR
M, Forum Nokia

3. ## Re: Problem in coding long SMS in 7 bit

Hi could you further explain how did you arrive with "A2" as your fill bits in your example?

Thank you so much.

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