Telstra one number and apple watch

Hi

I bought an SE apple watch last month with cellular planning to connect with Telstra's advertised One Number. After a month of calls back and forth Telstra have basically thrown their hands up and said it isn't going to work.

The only reason I bought the watch was so that I didn't have to take my phone with me when I exercised but could make a call on my watch if I got into any trouble.

Has anyone else had trouble connecting their watch to One Number? I am on a business plan and Telstra have told me that I shouldn't need to do any signing in - it should be automatic. Even if I do try to sign in it just goes back to a blank log in screen.

Thanks