Don't write long messages in an emergency. If it can't fit in one message, it probably doesn't matter. Instead of trying to predict everything, allow communication. Let them figure it out, don't command them.

Also, you might consider using existing messaging app. Then you can interact if have them install the app. Matrix might work. I think Matrix can do SMS.

19 SMS messages.

Does anyone still pay per text?

Why 3000 ? Set a character limit. If the detail is important they can just send 2.. or 10.

write a shorter emergency message?

"I was in a car accident, come to general hospital downtown"

Ok I understand the usecase now.

I would have used two textboxes, Title and description, but this works as well.