Text Message Length and Character Encoding

The text-message parameters should be encoded in the UTF-8 character set. All non-ASCII characters in command parameters should be encoded. The primary role of URL encoding is to encode URL strings into a form that can be passed via email or scripted-web links without altering the actual content in any way.

Supported character sets

GSM 03.38 encoding

The standard SMS mobile-phone character set is used universally to send text messages. You can send a longer text message by using only GSM 03.38 characters. The standard character set allows up to 160 characters, and includes the Latin alphabet and the most common accented forms, certain special characters, and the Greek alphabet. It includes the following characters:

@	Δ	SP	0	¡	P	¿	p
£	_	!	1	A	Q	a	q
$	Φ	"	2	B	R	b	r
¥	Γ	#	3	C	S	c	s
è	Λ	¤	4	D	T	d	t
é	Ω	%	5	E	U	e	u
ù	Π	&	6	F	V	f	v
ì	Ψ	'	7	G	W	g	w
ò	Σ	(	8	H	X	h	x
Ç	Θ	)	9	I	Y	i	y
LF	Ξ	*	:	J	Z	j	z
Ø	ESC	+	;	K	Ä	k	ä
ø	Æ	,	<	L	Ö	l	ö

Note: An escape character always precedes the characters { } \ ~ [ ] | ^ €, which therefore takes two characters to send.


When using non-GSM 03.38 characters, SMS transmits the message as a Unicode message. Unicode character support also provides the capability to send a message in Arabic, Japanese, Russian, Chinese and other alphabets.

Message length

GSM 03.38 encoding

Single text messages are limited to 160 characters, including spaces. However, to get around this restriction, messages could be linked together (up to 6 parts) to form one long message.

In reality, each concatenated text message is limited to 153 characters rather than 160 due to the need for user-data header (UDH) information. This applies only to messages that contain the standard GSM 03.38 character set. Mobile phones use UDH information to enable them to link long messages together so that they appear as a single SMS message in the recipients’ inboxes. 

Number of SMSs Total number of characters in the linked message
1 160
2 306
3 459
4 612
5 765
6 918 


Using Unicode (for Russian, Arabic and Chinese languages) restricts messages to a maximum of 70 characters per SMS. You can, however, send longer text messages, with our system by splitting them into two or at the most three separate text messages. The table below gives the maximum lengths of two or more parts of a concatenated Unicode text messages.

Number of SMSs Total number of characters in the linked message
1 70
2 134
3 201
4 268
5 335
6 402

The next step

Now you’ve learned more about Encoding. The next section will show you Old API Documentations.