Thank you Gary for your reply and the info.
If you don't know of any, and after 2 days of searching around I haven't found any, then I guess I need another idea.
The plug-in (wordpress-text-message) seemed promising, but it does not load properly and after several installs I am giving up on it.
The paid for SMS that I have seen are really set up for huge numbers,
at most we may have 1000, more likely half that, and only rarely.
As the site I am trying to use this on is a very local emergency awareness portal paid for out of my pocket.
Perhaps someone will make a plugin like this? One can only hope.
thanks again, if you have any 'great ideas' please feel free to contact me.