Exotel Support Center

The system counts the number of characters in your text message.

As you know, the standard length for text messages is 160, but using the Unicode the character set will decrease this length to 70 characters. So, even if you have 160 GSM characters, the message may be split if it contains one such symbol.

SMS Length

Single Text Message: The length of a single text message is 160 characters, including spaces.

Multi-part SMS: If you send an SMS whose length is over 160 characters, Exotel will treat it as a multi-part SMS. This multi-part SMS will be sent to your customer as a single SMS.

The maximum length of a single SMS in a multi-part SMS is 153 characters. This is due to the need for user-data headers (UDHs) information. User Data Header (UDH) is a binary structure that may be present at the start of a short message in the Short Message Service in GSM. It does not contain any text, but it specifies how the message should be formatted and processed. More information about the same is available here. 

Mobile phones use UDH information to enable them to link long messages together so that they appear as single SMS messages in the recipient's phone inbox.

You could send up to 1000 characters as a multipart message which will be split into 7 messages internally.

This refers only to messages that contain the standard GSM 03.38 character set (What this means has been explained in the section below).

Characters allowed in an SMS

The standard SMS mobile-phone character set is used universally to send text messages. The standard character (GSM 03.38 Encoding) set allows up to 160 characters, and includes few of the Roman alphabet and the most common accented forms, certain special characters, and few Greek alphabets. It includes the following characters:

@ £ \ $ ¥ è é ù ì ò Ç \ n Ø ø \ r Å å ? _ F " ? O ? ? S T ? Æ æ ß É ! \ " # ¤ % & ' ( ) * + , - ../ 0 1 2 3 4 5 6 7 8 9 : ; < = > ? ¡ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ? Ö Ñ Ü § ¿ a b c d e f g h I j k l m n o p q r s t u v w x y z ö ñ ü à ä Ä { } \ ~ [ ] |

SMS in languages other than English

When using non-GSM 03.38 characters (mentioned in the paragraph above), the SMS is transmitted as a Unicode message. The Unicode character support provides the ability to send a message in Hindi, Kannada, Tamil, etc.

If the message contains even a single Unicode character, the entire message will have to be converted into Unicode.

The maximum length of a Unicode SMS is 70 characters per SMS.

If your message runs longer than 70 characters, the system will treat it as a multi-part SMS. Your customer will see it delivered as a single message but Exotel will treat it as multiple SMS-es.

The maximum length of a single multi-part SMS is 67 characters. You could send up to 500 characters as a multipart message which will be split into 8 messages in the system..

You can calculate the length of your SMS using SMS Length Calculators here.