GSM Encoding and Special Characters – Wire2Air Customer Service Portal

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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