My T allows contact by mobile phone (txt or call). He has made me promise that if I am desperate I contct him and not the psych ER, which was really nice of him I think. I've txted him three times between sessions when I was feeling rather low. He will only respond that he read the message, but that has been enough to make me feel grounded. (The first time I txted he didn't reply at all because he figured he'd see me in a few days anyway. That didn't feel so good so I asked him to acknowledge that he gets a message.)