What is considered a single SMS message?
When sending SMS messages, the number of characters you can include depends on the type of encoding used. Understanding this is important, as it directly affects how many message segments your text will be split into, and how many of your SMS limit will be consumed.
What is an SMS segment?
In MightyCall, a single message is counted as one SMS segment. A segment represents a portion of your message that fits within the telecom standard character limit.
- A standard SMS segment allows up to 160 characters;
- Spaces and punctuation are counted as characters.
If your message exceeds the limit, it will be split into multiple segments and billed accordingly.
GSM and Unicode encodings
The default encoding for SMS is GSM-7, which supports the most commonly used characters:
- Latin letters (A–Z, a–z);
- Numbers (0–9);
- Common punctuation and symbols.
Each GSM character uses one character space, allowing up to:
- 160 characters per single segment;
- 153 characters per segment when the message is split into multiple segments (concatenated SMS).
If your message includes any non-GSM character, the encoding automatically switches to Unicode (UCS-2). Examples of Unicode characters:
- Emojis;
- Non-Latin alphabets (e.g., Cyrillic, Arabic, Chinese);
- Special symbols (e.g., smart quotes, certain accented letters).
In this case:
- A single segment is limited to 70 characters;
- Concatenated messages allow 67 characters per segment.
Even a single Unicode character in the message will change the encoding to Unicode and apply this limit to the entire message.
Why encoding matters
Using Unicode significantly reduces the number of characters per segment, which can increase the total number of segments used for a single message.
We recommend checking the number of characters and the encoding of your messages in any SMS counter (for example, the one I mentioned earlier) before sending them. If you find a Unicode character, replace it with a GSM one. You can find the list of GSM characters here.