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GSM Encoding and Special Characters

Standard SMS can contain 160 characters. However, the characters must be part of the so-called 7-bit default alphabet as specified by GSM 3.38 character set. 

This alphabet contains all ASCII characters and some accented characters.

For example, u umlaut (ü) and e with grave (è) are in this set. 

Using any character not in this set, will require the SMS to be treated as a Unicode SMS and limit the length of the SMS to 70 characters due to the different character encoding. See Article on how to send Unicode messages:

Specific common characters that you should avoid using to ensure your message is sent using the more efficient GSM character set are:

`              should be '
               this apostrophe is formatted by MS Office.
                Note the difference between  and '
              should be "
              should be "
~             should be -
¬             should be -
|
              should be avoided altogether, otherwise use an uppercase I

 You can use the following tool to replace some of the unnecessary Unicode characters with equivalent GSM characters: http://mzone.wire2air.com/mserver/vas/UnicodeDetect.aspx

The GSM 03.38 7 bit character set

Dec

Hex

Char

Dec

Hex

Char

Dec

Hex

Char

Dec

Hex

Char

0

0

@

16

10

Δ

32

20

SP

48

30

0

1

1

£

17

11

_

33

21

!

49

31

1

2

2

$

18

12

Φ

34

22

"

50

32

2

3

3

¥

19

13

Γ

35

23

#

51

33

3

4

4

è

20

14

Λ

36

24

¤

52

34

4

5

5

é

21

15

Ω

37

25

%

53

35

5

6

6

ù

22

16

Π

38

26

&

54

36

6

7

7

ì

23

17

Ψ

39

27

'

55

37

7

8

8

ò

24

18

Σ

40

28

(

56

38

8

9

9

Ç

25

19

Θ

41

29

)

57

39

9

10

A

LF

26

1A

Ξ

42

2A

*

58

3A

:

11

B

 

27

1B

<ESC>

43

2B

+

59

3B

;

12

C

ø

28

1C

Æ

44

2C

,

60

3C

< 

13

D

CR

29

1D

æ

45

2D

-

61

3D

=

14

E

Å

30

1E

ß

46

2E

.

62

3E

> 

15

F

å

31

1F

É

47

2F

/

63

3F

?

Dec

Hex

Char

Dec

Hex

Char

Dec

Hex

Char

Dec

Hex

Char

64

40

¡

80

50

P

96

60

¿

112

70

p

65

41

A

81

51

Q

97

61

a

113

71

q

66

42

B

82

52

R

98

62

b

114

72

r

67

43

C

83

53

S

99

63

c

115

73

s

68

44

D

84

54

T

100

64

d

116

74

t

69

45

E

85

55

U

101

65

e

117

75

u

70

46

F

86

56

V

102

66

f

118

76

v

71

47

G

87

57

W

103

67

g

119

77

w

72

48

H

88

58

X

104

68

h

120

78

x

73

49

I

89

59

Y

105

69

i

121

79

y

74

4A

J

90

5A

Z

106

6A

j

122

7A

z

75

4B

K

91

5B

Ä

107

6B

k

123

7B

ä

76

4C

L

92

5C

Ö

108

6C

l

124

7C

ö

77

4D

M

93

5D

Ñ

109

6D

m

125

7D

ñ

78

4E

N

94

5E

Ü

110

6E

n

126

7E

ü

79

4F

O

95

5F

 

111

6F

o

127

7F

à

Some additional characters can be sent using the <ESC> (0x1B) code in the above table plus an additional character; these extended characters are known as the Extended GSM character set and require 2 standard GSM characters per extended GSM character due to requiring the escape character prefix.

Note: Some of the characters will not be displayed correctly due to handset limitations

The Extended GSM character set

 

Dec

Hex

Char

27, 101

1B, 65

27, 10

1B, 0A

<FF>

27, 60

1B, 3C

[

27, 47

1B, 2F

\

27, 62

1B, 3E

]

27, 20

1B, 14

^

27, 40

1B, 28

{

27, 64

1B, 40

|

27, 41

1B, 29

}

27, 61

1B, 3D

~

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