By default a regular SMS length is set to 160 characters.
If the message is greater than this limit, the message becomes a multipart one and the scale is changed. The character limit is 153 characters for each message (the remaining 7 characters being there for bridging the gap between all the words).
If the Unicode option is enabled, every character counts for two and :
- the maximum length of a simple message goes to 70 characters
- the maximum length of a long messages goes to 63 characters