Out of the 5 t's I've had, only one was available in crisis. XT's voice mail had a feature where if you pressed a certain number after your message, it marked it as urgent and he would get back to you quicker. After figuring out that there was NO way I would ever consider a message of mine urgent, he got me to text him instead of voice mail. Part of that was to help with a speech impediment I have and a fear of voice recording. Text was the only way for me to get a very quick call back or even just a response.
The few times I texted were things like: "I am sort of in a bad place". He'd text back within a few minutes: "can I call you, or would you like to come in?" One thing about XT is that he was really good at diffusing a situation on the phone. When he went on vacation he would tell me "You can text me, because I know you aren't the sort of person to overuse it". I never texted him when he was on vaca...or on a weekend, there is no way I would ever interrupt his time off.

Over the years I have found that a crisis can be held off until the next work day, no matter how bad it seems at the time.