Key takeaways
- A message in the standard GSM-7 alphabet holds 160 characters; one that needs Unicode holds 70.
- Longer messages are split into segments of 153 (GSM-7) or 67 (Unicode) characters, because each segment carries a small header.
- One emoji or one curly quote can switch the whole message to Unicode.
- Check the segment count before a campaign: it drives cost as well as delivery.
Two encodings, two limits
Most text uses the GSM-7 alphabet, which covers the basic Latin letters, digits, common punctuation and several accented letters. In GSM-7 one message holds 160 characters.
If the text contains even one character outside that alphabet, the whole message is sent as Unicode (UCS-2), and one message holds only 70 characters.
What breaks GSM-7
A few characters, such as the euro sign, square brackets and the curly braces, are in GSM-7 but count as two characters each.
The Danish letters æ, ø and å are part of GSM-7, so ordinary Danish text normally stays in the cheaper encoding.
- Emoji and most symbols
- Curly quotes, long dashes and other characters pasted from word processors
- Some accented letters (many are included, but not all)
- Non-Latin scripts such as Greek, Cyrillic or Arabic
Segments: how long messages are split
A longer message is sent as several segments that the phone joins together again. Each segment needs a small header, so the usable length drops to 153 characters per segment in GSM-7 and 67 in Unicode.
A 170-character message in GSM-7 is therefore two segments. A 75-character message with an emoji is also two segments.
How to keep messages short and cheap
- Write for one segment: 160 characters in GSM-7
- Replace curly quotes and long dashes with plain ones before sending
- Use emoji only where they add something, and expect a shorter limit
- Put links last and keep them short
- Let your system count segments before it sends, and show the count in your campaign tool
How ZafeConnect fits
ZafeConnect charges only for delivered messages, with no setup, system or operating fees and no subscription, and the price list shows the list price per message, excluding VAT. A message that spans several segments is generally billed per segment, so check how your agreement counts them.