# GSM-7

> GSM-7 is the default 7-bit SMS alphabet: 128 basic characters covering Latin letters, digits and common punctuation, allowing 160 characters in one message (153 per part when concatenated).

GSM-7 packs 7-bit characters into the 140-byte payload of an SMS, which is how 160 fit in one message. The basic table holds the Latin alphabet, digits, common punctuation, a few accented letters (é, ñ, ü, à, ö…) and some Greek capitals. A second table of [extended characters](https://smsmeteor.com/glossary/gsm-extended-characters) (such as the euro sign, square brackets, braces, backslash) costs two positions each.

One character outside both tables, a curly quote, an em dash, an emoji, a Cyrillic or Arabic letter, switches the whole message to [UCS-2](https://smsmeteor.com/glossary/ucs-2) and halves its capacity. That is the single most common cause of an unexpectedly doubled campaign cost.

At SMSMeteor: the composer and the API response report the encoding and segment count before anything is sent; GSM-7 holds 160 characters (153 per part when concatenated).

Related terms: [UCS-2 (Unicode SMS)](https://smsmeteor.com/glossary/ucs-2), [SMS segment](https://smsmeteor.com/glossary/segment), [GSM extended characters](https://smsmeteor.com/glossary/gsm-extended-characters), [Character counter](https://smsmeteor.com/glossary/character-counter)

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Source: https://smsmeteor.com/glossary/gsm-7 (HTML). Generated by SMSMeteor from the same data as the page. Summary of the whole site: https://smsmeteor.com/llms.txt