Twilio supports SMS with a maximum length of up to 1,600 characters. (Many people keep in mind that the SMS size limit is 160 characters.)
On the smartphone, it is seen as a long text, but technically, several SMS messages (segments) are unified (concatenated).
The size of each segment will be defined, considering how the message was encoded.
- A message without accent: each segment of the message will have 153 characters—text encoding.
- Accented message: each segment will have 67 characters. UCS-2 encoding.
Twilio's billing is based on the number of message segments. For example, if you pay $ 0.057 for SMS on Twilio, this amount corresponds to the segment.
To find out the number of segments of your SMS, use this tool to paste the text of your message: http://chadselph.github.io/smssplit/.
Source: https://www.twilio.com/docs/glossary/what-is-gsm-7-character-encoding