SMS Encoding and Character Support

What Are the Rules for SMS Character Encoding and Message Length?

This document provides information about the character encoding support and message length calculations for SMS messages processed through our system. It delineates the handling of Plain Text (utilizing GSM and ASCII encoding) and Unicode (UTF-16 encoding) messages, ensuring users understand how to optimize their message content within the constraints of standard and concatenated SMS messages.

Plain Text SMS Messages

For messages considered as Plain Text by our system, the following specifications apply based on GSM encoding:

Single SMS Message: Allows up to 160 characters.
Concatenated SMS Messages:
- 2 parts: Up to 306 characters.
- 3 parts: Up to 459 characters.
- 4 parts: Up to 612 characters.
- 5 parts: Up to 765 characters.

Supported Characters

Our system recognizes a combined set of GSM and ASCII characters as plain text. The supported characters include:

Special characters: @ £ $ ¥ è é ù ì ò Ç Ø ø Å å Δ _ Φ Γ Λ Ω Π Ψ Σ Θ Ξ Æ æ ß É ! " # % & ' ( ) * + , - . /
Numeric digits: 0 1 2 3 4 5 6 7 8 9
Punctuation and symbols: : ; < = > ? ¡ [ ] ^ { | } ~ space key
Alphabetic characters: Both uppercase and lowercase letters from A to Z and a to z, including special European characters such as Ä Ö Ñ Ü ä ö ñ ü à.

Additionally, a select set of Unicode characters can be converted and supported as plain text:

Original Unicode set: “ ” ’ ‘ Ç ç Ğ ğ Ş ş Ö ö Ü ü –

Converted to plain text set: " " ' ' C c G g S s O o U u -

Unicode SMS Messages

Messages containing characters outside the above-listed sets are treated as Unicode messages by our system, using UTF-16 encoding. The message length calculations for Unicode SMS messages are as follows:

Single SMS Message: Allows up to 70 characters.
Concatenated SMS Messages:
- 2 parts: Up to 134 characters.
- 3 parts: Up to 201 characters.
- 4 parts: Up to 268 characters.
- 5 parts: Up to 335 characters.