GSM-7 alphabet

Each GSM-7 sign fits into 7 bits. Since an SMS payload is 140 bytes, the calculation lands exactly on 160 characters: that is where the text message's historic limit comes from.

This set covers the basic Latin letters, the digits, the usual punctuation and a handful of accents, but not all of them. Slipping in a character absent from the table tips the message into UCS-2 and sharply cuts its capacity, hence the habit of removing accents before sending.