Who I have the same questioned this topic

Any time I try to send a text to a 5 digit number, it fails. It simply stays in the sending state and never sends. I have noticed this previously but now it is a problem as I NEED this function for my employment and being on-call.

I have seen this issue posted a few times before with no resolution from Verizon. I use the standard messaging app that comes with my Note 5. 

It is unacceptable and I pay good, hard worked for money, to have this small function not work.