What is an SMS Segment

An SMS segment refers to a portion of a text message sent via Short Message Service (SMS). Here's how it works:

What is an SMS Segment?

• Standard SMS messages are limited to 160 characters when using the GSM-7 encoding (the most common character set for SMS).
• If you use Unicode characters (like emojis or non-Latin scripts), the limit drops to 70 characters per segment.
• When a message exceeds these limits, it's split into multiple segments and sent as a concatenated SMS.

Example:

• A message with 300 GSM-7 characters would be split into 2 segments:
  • Each segment can hold 153 characters (because 7 characters are used for metadata to reassemble the message).
  • So: 300 characters → 153 + 147 → 2 segments.

Why It Matters:

• Cost: SMS providers charge per segment, not per message.
• Delivery: Some older phones or networks may not reassemble segments correctly.
• Analytics: Businesses track segments to manage costs and optimize message length.