Siemens MC55 AT manual 2 UCS2 and GSM data coding and conversion for SMS text mode, Gsm

In the event that an MS receives a code where a symbol is not represented in Figure 1.2, Extension character table of GSM 03.38 alphabet the MS shall display the character shown in the main default 7 bit alphabet table (see Figure 1.1, Main character table of GSM 03.38 alphabet).

1.5.2UCS2 and GSM data coding and conversion for SMS text mode

This section provides basic information on how to handle input and output character conversion for SMS text mode and Remote-SAT if internal (TA) and external (TE) character representation differ, i.e. if the Data Coding Scheme and the TE character use different coding.

1.5.2.1Implementing output of SIM data to Terminal (direction TA to TE)

Used character set	DCS = 7 bit	DCS = 8 bit	DCS = 16 bit
	GSM	Data	UCS2
GSM	Case 1	Case 2	Case 3
	GSM (1:1)	8 bit to IRA (1:2)	UCS2 to IRA (2:4)
UCS2	Case 4	Case 5	Case 6
	GSM to IRA (1:4)	8 bit to IRA (1:4)	UCS2 to IRA (2:4)

Note: The ratio of SIM bytes to output bytes is given in parentheses.

Case 1

Every GSM character is sent to the TE as it is (8-bit value with highest bit set to zero). Example: 47'H, 53'H, 4D'H → 47'H, 53'H, 4D'H, displayed as "GSM"

Case 2

Every data byte is sent to the TE as 2 IRA characters each representing a halfbyte.

Example: B8'H (184 decimal) → 42'H, 38'H, displayed as "B8"

Case 3

Every 16-bit UCS2 value is sent to the TE as 4 IRA characters.

Example: C4xA7'H (50343 decimal) → 43'H, 34'H, 41'H, 37'H, displayed as "C4A7"

Problem: An odd number of bytes leads to an error because there are always two bytes needed for each USC2 character

Case 4

Every GSM character is sent to the TE as 4 IRA characters to show UCS2 in text mode. Example: 41'H ("A") → 30'H, 30'H, 34'H, 31'H, displayed as "0041"

Case 5

Every data byte is sent to the TE as IRA representation of UCS2 (similar to case 4). Example: B2'H → 30'H, 30'H, 42'H, 32'H, displayed as "00B2"

Case 6

Every 16-bit value is sent to the TE as IRA representation of it. It is assumed that number of bytes is even. Example: C3x46'H → 43'H, 33'H, 34'H, 36'H, displayed as "C346"

MC55_ATC_V04.00	Page 23 of 475	3/17/06
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