Message Segment Visualisation

GSM-7 Encoding

GSM-7 is the most commonly used encoding format for SMS messaging. It is designed to maximize character capacity while supporting a standard set of characters, including:

Supported Characters in GSM-7:

Some special characters belong to the GSM-7 extended set and require an escape sequence (2 bytes), reducing the number of characters per segment, such as:

Key Features:

1. 

   Efficient encoding using 7 bits per character.

2. 

   Up to 160 characters per SMS segment.

3. 

   Ideal for standard English messages or limited special characters.

UCS-2 Encoding:

UCS-2 (Universal Character Set - 2 Bytes) is a 16-bit encoding format for SMS that supports a broader range of characters, including non-Latin scripts and complex symbols.

Examples of Characters Supported by UCS-2 (Beyond GSM-7):

Key Features:

1. 

   Comprehensive global language and symbol support.

2. 

   Essential for multilingual audiences and expressive messaging.

3. 

   Reduced character capacity compared to GSM-7.

The choice of encoding impacts the number of characters allowed per SMS segment:

1. 

   GSM-7: 160 characters for a single segment. If split, subsequent segments allow 153 characters each due to the header.

2. 

   UCS-2: 70 characters for a single segment, with subsequent segments allowing 67 characters each.

For cost efficiency, use GSM-7 when possible. Choose UCS-2 for messages containing special characters, emojis, or non-Latin scripts.