you should tell us what "per segment" means. Never heard of it. I use twilio mostly.

Twilio also charges per segment, they are probably not transparent. So a segment means 160 characters (It’s a bit more complicated than that).

So if you want to send an 320 characters long SMS. You are sending two segments.

Let me know if it makes sense?

that makes sense. you should put a * with a defintiion or something

I'll add a tooltip.

Have you ever had an SMS get chunked into two?

A segment is the character (really byte) limit for a single message.