Data Coding Scheme

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Data Coding Scheme is a one-octet field in Short Messages (SM) and Cell Broadcast Messages (CB) which carries a basic information how the recipient handset should process the received message. The information includes:

  • the character set or message coding which determines the encoding of the message user data
  • the message class which determines to which component of the Mobile Station (MS) or User Equipment (UE) should be the message delivered
  • the request to automatically delete the message after reading
  • the state of flags indicating presence of unread voicemail, fax, e-mail or other messages
  • the indication that the message content is compressed
  • the language of the cell broadcast message

The field is described in 3GPP 23.040 and 3GPP 23.038 under the name TP-DCS.

Message Character Sets[edit]

A special 7-bit encoding called the GSM 7 bit default alphabet was designed for the Short Message System in GSM. The alphabet contains the most-often used symbols from most Western-European languages (and some Greek uppercase letters). Some ASCII characters and the Euro sign did not fit into the GSM 7-bit default alphabet and must be encoded using two septets. These characters form GSM 7 bit default alphabet extension table. Support of the GSM 7-bit alphabet is mandatory for GSM handsets and network elements.[1]

Languages which use Latin script, but use characters which are not present in the GSM 7-bit default alphabet, often replace missing characters with diacritic marks with corresponding characters without diacritics, which causes not entirely satisfactory user experience, but is often accepted. In order to include these missing characters the 16-bit UTF-16 (in GSM called UCS-2) encoding may be used at the price of reducing the length of a (non-segmented) message from 160 to 70 characters.

The messages in Chinese, Korean or Japanese languages must be encoded using the UTF-16 character encoding. The same was also true for other languages using non-Latin scripts like Russian, Arabic, Hebrew and various Indian languages. In 3GPP TS 23.038 8.0.0 published in 2008 a new feature, an extended National language shift table was introduced, which in the version 11.0.0 published in 2012 covers Turkish, Spanish, Portuguese, Bengali, Gujarati, Hindi, Kannada, Malayalam, Oriya, Punjabi, Tamil, Telugu and Urdu languages. The mechanism replaces GSM 7-bit default alphabet code table and/or extended table with a national table(s) according to special information elements in User Data Header. The non-segmented message using national language shift table(s) may carry up to 155 (or 153) 7-bit characters.

GSM recognizes only two encodings for text messages and one encoding for binary messages:

  • GSM 7-bit default alphabet (which includes using of National language shift tables as well)
  • UCS-2
  • 8-bit data

Message Classes[edit]

The TP-DCS octet has a complex syntax to allow carrying of other information; the most notable are message classes:

Message Classes
Value Message Class
0 0 0 - Flash messages
0 1 1 - ME-specific
1 0 2 - SIM / USIM specific
1 1 3 - TE-specific

Flash messages are received by a mobile phone even though it has full memory. They are not stored in the phone, they just displayed on the phone display.

Other Features[edit]

Automatic Deletion after Reading[edit]

The handset should delete any message received with a TP-DCS value falling to the "Message Marked for Automatic Deletion Coding Group" after user has read it.

Message Waiting Indication[edit]

Message Waiting Indication group of DCS values serves to set or reset flags indicating presence of unread voicemail, fax, e-mail or other messages.

Data Compression[edit]

A special DCS value also allows message compression, but it perhaps is not used by any operator.

DCS Values[edit]

SMS Data Coding Scheme[edit]

The values of TP-DCS are defined in GSM recommendation 03.38.[1]

Coding Group: General Data Coding
DCS
hex dec
Character Set Message Class Compressed Reserved Because
00 0 GSM 7 bit Default -
01 1 GSM 7 bit Default - Bits 1 and 0 have value 1 but no message class present
02 2 GSM 7 bit Default - Bits 1 and 0 have value 2 but no message class present
03 3 GSM 7 bit Default - Bits 1 and 0 have value 3 but no message class present
04 4 8 bit data Default -
05 5 8 bit data Default - Bits 1 and 0 have value 1 but no message class present
06 6 8 bit data Default - Bits 1 and 0 have value 2 but no message class present
07 7 8 bit data Default - Bits 1 and 0 have value 3 but no message class present
08 8 UCS2 Default -
09 9 UCS2 Default - Bits 1 and 0 have value 1 but no message class present
0A 10 UCS2 Default - Bits 1 and 0 have value 2 but no message class present
0B 11 UCS2 Default - Bits 1 and 0 have value 3 but no message class present
0C 12 (reserved) Default - Reserved character set
0D 13 (reserved) Default - Reserved character set

Bits 1 and 0 have value 1 but no message class present

0E 14 (reserved) Default - Reserved character set

Bits 1 and 0 have value 2 but no message class present

0F 15 (reserved) Default - Reserved character set

Bits 1 and 0 have value 3 but no message class present

10 16 GSM 7 bit Class 0 (Flash message) -
11 17 GSM 7 bit Class 1 (ME-specific) -
12 18 GSM 7 bit Class 2 (SIM/USIM-specific) -
13 19 GSM 7 bit Class 3 (TE-specific) -
14 20 8 bit data Class 0 (Flash message) -
15 21 8 bit data Class 1 (ME-specific) -
16 22 8 bit data Class 2 (SIM/USIM-specific) -
17 23 8 bit data Class 3 (TE-specific) -
18 24 UCS2 Class 0 (Flash message) -
19 25 UCS2 Class 1 (ME-specific) -
1A 26 UCS2 Class 2 (SIM/USIM-specific) -
1B 27 UCS2 Class 3 (TE-specific) -
1C 28 (reserved) Class 0 (Flash message) - Reserved character set
1D 29 (reserved) Class 1 (ME-specific) - Reserved character set
1E 30 (reserved) Class 2 (SIM/USIM-specific) - Reserved character set
1F 31 (reserved) Class 3 (TE-specific) - Reserved character set
20 32 GSM 7 bit Default +
21 33 GSM 7 bit Default + Bits 1 and 0 have value 1 but no message class present
22 34 GSM 7 bit Default + Bits 1 and 0 have value 2 but no message class present
23 35 GSM 7 bit Default + Bits 1 and 0 have value 3 but no message class present
24 36 8 bit data Default + Compression set but Character set can't be compressed
25 37 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 1 but no message class present

26 38 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 2 but no message class present

27 39 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 3 but no message class present

28 40 UCS2 Default + Compression set but Character set can't be compressed
29 41 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 1 but no message class present

2A 42 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 2 but no message class present

2B 43 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 3 but no message class present

2C 44 (reserved) Default + Reserved character set
2D 45 (reserved) Default + Reserved character set

Bits 1 and 0 have value 1 but no message class present

2E 46 (reserved) Default + Reserved character set

Bits 1 and 0 have value 1 but no message class present

2F 47 (reserved) Default + Reserved character set

Bits 1 and 0 have value 1 but no message class present

30 48 GSM 7 bit Class 0 (Flash message) +
31 49 GSM 7 bit Class 1 (ME-specific) +
32 50 GSM 7 bit Class 2 (SIM/USIM-specific) +
33 51 GSM 7 bit Class 3 (TE-specific) +
34 52 8 bit data Class 0 (Flash message) + Compression set but Character set can't be compressed
35 53 8 bit data Class 1 (ME-specific) + Compression set but Character set can't be compressed
36 54 8 bit data Class 2 (SIM/USIM-specific) + Compression set but Character set can't be compressed
37 55 8 bit data Class 3 (TE-specific) + Compression set but Character set can't be compressed
38 56 UCS2 Class 0 (Flash message) + Compression set but Character set can't be compressed
39 57 UCS2 Class 1 (ME-specific) + Compression set but Character set can't be compressed
3A 58 UCS2 Class 2 (SIM/USIM-specific) + Compression set but Character set can't be compressed
3B 59 UCS2 Class 3 (TE-specific) + Compression set but Character set can't be compressed
3C 60 (reserved) Class 0 (Flash message) + Reserved character set
3D 61 (reserved) Class 1 (ME-specific) + Reserved character set
3E 62 (reserved) Class 2 (SIM/USIM-specific) + Reserved character set
3F 63 (reserved) Class 3 (TE-specific) + Reserved character set
Coding Group: Message Marked for Automatic Deletion
DCS
hex dec
Character Set Message Class Compressed Reserved Because
40 64 GSM 7 bit Default -
41 65 GSM 7 bit Default - Bits 1 and 0 have value 1 but no message class present
42 66 GSM 7 bit Default - Bits 1 and 0 have value 2 but no message class present
43 67 GSM 7 bit Default - Bits 1 and 0 have value 3 but no message class present
44 68 8 bit data Default -
45 69 8 bit data Default - Bits 1 and 0 have value 1 but no message class present
46 70 8 bit data Default - Bits 1 and 0 have value 2 but no message class present
47 71 8 bit data Default - Bits 1 and 0 have value 3 but no message class present
48 72 UCS2 Default -
49 73 UCS2 Default - Bits 1 and 0 have value 1 but no message class present
4A 74 UCS2 Default - Bits 1 and 0 have value 2 but no message class present
4B 75 UCS2 Default - Bits 1 and 0 have value 3 but no message class present
4C 76 (reserved) Default - Reserved character set
4D 77 (reserved) Default - Reserved character set

Bits 1 and 0 have value 1 but no message class present

4E 78 (reserved) Default - Reserved character set

Bits 1 and 0 have value 2 but no message class present

4F 79 (reserved) Default - Reserved character set

Bits 1 and 0 have value 3 but no message class present

50 80 GSM 7 bit Class 0 (Flash message) -
51 81 GSM 7 bit Class 1 (ME-specific) -
52 82 GSM 7 bit Class 2 (SIM/USIM-specific) -
53 83 GSM 7 bit Class 3 (TE-specific) -
54 84 8 bit data Class 0 (Flash message) -
55 85 8 bit data Class 1 (ME-specific) -
56 86 8 bit data Class 2 (SIM/USIM-specific) -
57 87 8 bit data Class 3 (TE-specific) -
58 88 UCS2 Class 0 (Flash message) -
59 89 UCS2 Class 1 (ME-specific) -
5A 90 UCS2 Class 2 (SIM/USIM-specific) -
5B 91 UCS2 Class 3 (TE-specific) -
5C 92 (reserved) Class 0 (Flash message) - Reserved character set
5D 93 (reserved) Class 1 (ME-specific) - Reserved character set
5E 94 (reserved) Class 2 (SIM/USIM-specific) - Reserved character set
5F 95 (reserved) Class 3 (TE-specific) - Reserved character set
60 96 GSM 7 bit Default +
61 97 GSM 7 bit Default + Bits 1 and 0 have value 1 but no message class present
62 98 GSM 7 bit Default + Bits 1 and 0 have value 2 but no message class present
63 99 GSM 7 bit Default + Bits 1 and 0 have value 3 but no message class present
64 100 8 bit data Default + Compression set but Character set can't be compressed
65 101 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 1 but no message class present

66 102 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 2 but no message class present

67 103 8 bit data Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 3 but no message class present

68 104 UCS2 Default + Compression set but Character set can't be compressed
69 105 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 1 but no message class present

6A 106 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 2 but no message class present

6B 107 UCS2 Default + Compression set but Character set can't be compressed

Bits 1 and 0 have value 3 but no message class present

6C 108 (reserved) Default + Reserved character set
6D 109 (reserved) Default + Reserved character set

Bits 1 and 0 have value 1 but no message class present

6E 110 (reserved) Default + Reserved character set

Bits 1 and 0 have value 2 but no message class present

6F 111 (reserved) Default + Reserved character set

Bits 1 and 0 have value 3 but no message class present

70 112 GSM 7 bit Class 0 (Flash message) +
71 113 GSM 7 bit Class 1 (ME-specific) +
72 114 GSM 7 bit Class 2 (SIM/USIM-specific) +
73 115 GSM 7 bit Class 3 (TE-specific) +
74 116 8 bit data Class 0 (Flash message) + Compression set but Character set can't be compressed
75 117 8 bit data Class 1 (ME-specific) + Compression set but Character set can't be compressed
76 118 8 bit data Class 2 (SIM/USIM-specific) + Compression set but Character set can't be compressed
77 119 8 bit data Class 3 (TE-specific) + Compression set but Character set can't be compressed
78 120 UCS2 Class 0 (Flash message) + Compression set but Character set can't be compressed
79 121 UCS2 Class 1 (ME-specific) + Compression set but Character set can't be compressed
7A 122 UCS2 Class 2 (SIM/USIM-specific) + Compression set but Character set can't be compressed
7B 123 UCS2 Class 3 (TE-specific) + Compression set but Character set can't be compressed
7C 124 (reserved) Class 0 (Flash message) + Reserved character set
7D 125 (reserved) Class 1 (ME-specific) + Reserved character set
7E 126 (reserved) Class 2 (SIM/USIM-specific) + Reserved character set
7F 127 (reserved) Class 3 (TE-specific) + Reserved character set
Coding Group: Reserved
DCS
hex dec
Character Set Message Class Compressed Reserved Because
80 128 (not defined) Default - Reserved coding group
... up to ...
BF 191 (not defined) Default - Reserved coding group
Coding Group: Message Waiting Info: Discard Message
DCS
hex dec
Character Set Message Waiting Information Compressed Reserved Because
C0 192 (not defined) Voicemail Inactive -
C1 193 (not defined) Fax Inactive -
C2 194 (not defined) E-mail Inactive -
C3 195 (not defined) Other Inactive -
C4 196 (not defined) Voicemail Inactive - Value of bit 2
C5 197 (not defined) Fax Inactive - Value of bit 2
C6 198 (not defined) E-mail Inactive - Value of bit 2
C7 199 (not defined) Other Inactive - Value of bit 2
C8 200 (not defined) Voicemail Active -
C9 201 (not defined) Fax Active -
CA 202 (not defined) E-mail Active -
CB 203 (not defined) Other Active -
CC 204 (not defined) Voicemail Active - Value of bit 2
CD 205 (not defined) Fax Active - Value of bit 2
CE 206 (not defined) E-mail Active - Value of bit 2
CF 207 (not defined) Other Active - Value of bit 2
Coding Group: Message Waiting Info: Store Message
DCS
hex dec
Character Set Message Waiting Information Compressed Reserved Because
D0 208 GSM 7 bit Voicemail Inactive -
D1 209 GSM 7 bit Fax Inactive -
D2 210 GSM 7 bit E-mail Inactive -
D3 211 GSM 7 bit Other Inactive -
D4 212 GSM 7 bit Voicemail Inactive - Value of bit 2
D5 213 GSM 7 bit Fax Inactive - Value of bit 2
D6 214 GSM 7 bit E-mail Inactive - Value of bit 2
D7 215 GSM 7 bit Other Inactive - Value of bit 2
D8 216 GSM 7 bit Voicemail Active -
D9 217 GSM 7 bit Fax Active -
DA 218 GSM 7 bit E-mail Active -
DB 219 GSM 7 bit Other Active -
DC 220 GSM 7 bit Voicemail Active - Value of bit 2
DD 221 GSM 7 bit Fax Active - Value of bit 2
DE 222 GSM 7 bit E-mail Active - Value of bit 2
DF 223 GSM 7 bit Other Active - Value of bit 2
E0 224 UCS2 Voicemail Inactive -
E1 225 UCS2 Fax Inactive -
E2 226 UCS2 E-mail Inactive -
E3 227 UCS2 Other Inactive -
E4 228 UCS2 Voicemail Inactive - Value of bit 2
E5 229 UCS2 Fax Inactive - Value of bit 2
E6 230 UCS2 E-mail Inactive - Value of bit 2
E7 231 UCS2 Other Inactive - Value of bit 2
E8 232 UCS2 Voicemail Active -
E9 233 UCS2 Fax Active -
EA 234 UCS2 E-mail Active -
EB 235 UCS2 Other Active -
EC 236 UCS2 Voicemail Active - Value of bit 2
ED 237 UCS2 Fax Active - Value of bit 2
EE 238 UCS2 E-mail Active - Value of bit 2
EF 239 UCS2 Other Active - Value of bit 2
Coding Group: Data Coding/Message Class
DCS
hex dec
Character Set Message Class Compressed Reserved Because
F0 240 GSM 7 bit Class 0 (Flash message) -
F1 241 GSM 7 bit Class 1 (ME-specific) -
F2 242 GSM 7 bit Class 2 (SIM/USIM-specific) -
F3 243 GSM 7 bit Class 3 (TE-specific) -
F4 244 8 bit data Class 0 (Flash message) -
F5 245 8 bit data Class 1 (ME-specific) -
F6 246 8 bit data Class 2 (SIM/USIM-specific) -
F7 247 8 bit data Class 3 (TE-specific) -
F8 248 GSM 7 bit Class 0 (Flash message) - Value of bit 3
F9 249 GSM 7 bit Class 1 (ME-specific) - Value of bit 3
FA 250 GSM 7 bit Class 2 (SIM/USIM-specific) - Value of bit 3
FB 251 GSM 7 bit Class 3 (TE-specific) - Value of bit 3
FC 252 8 bit data Class 0 (Flash message) - Value of bit 3
FD 253 8 bit data Class 1 (ME-specific) - Value of bit 3
FE 254 8 bit data Class 2 (SIM/USIM-specific) - Value of bit 3
FF 255 8 bit data Class 3 (TE-specific) - Value of bit 3

iDEN mobile standard uses values F716 and F816 in a special way.

CBS Data Coding Scheme[edit]

For the DCS values in Cell Broadcast Messages see GSM recommendation 03.38.[1]

See also[edit]

References[edit]

  1. ^ a b c 3GPP TS 23.038, Alphabets and language-specific information.