A standard SMS length has a limit of 160 characters. If you use unicode characters or UCS2 (e.g. for Thai, Arabic, Chinese and Japanese), it will decrease to 70 characters.
Every additional SMS after the first 160 characters (or 70 unicode characters) is referred to as a concatenated message part. The maximum number of concatenated message parts in a single text message is 20 parts.
Additionally, do note that the maximum length per concatenated message part is slightly reduced due to the inclusion of concatenation headers:
- 153 characters for ASCII
- 66 characters for Unicode