Incorrect segment counting

[kasyrm]

I spotted a similar issue to this one: https://github.com/TwilioDevEd/message-segment-calculator/issues/18.

When providing a message like this one: ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]

Segment calculator shows it's 3 segments.

It's 153 scalars counted as 306 characters. That's 2142 bits for characters + 96 bits for 2 headers. That should add up to 2238 bits so still within 2 segments.

But when adding the last character of this string another header is added and the message takes up 2286 bits: 3 segments.

There are other calculators that show this as 2 segments (https://sakari.io/sms-length-calculator/)

But when sending the message on Twillio it is sent as 3 segments. So I have been wondering which is correct and what is causing this behaviour.