The character limit for a single SMS message is 160 Latin or 70 Cyrillic characters.
Important: if the message with Latin characters contains numbers or specific letters (ä, ü, ō, ę, ă), the limit of one SMS is 70 characters.
Large messages are split into individual SMS messages, each of which has a special "UDH" header. It allows re-creating the large message at the receiving end. In this case, the limit of SMS will not exceed 67 Cyrillic or 153 Latin characters.
There are also some special characters that are encoded using 2 characters. For example: {, }, [, ], ^, ~, \, |.
The maximum number of characters is 536 in Cyrillic and 1224 in Latin.