I don't see a difference between them and the crisis line? Do they know you at all? What are the benefits?

Ive learned long ago never to call when in crisis- an innocent word can send to hell. I am not triggered easily, but there are few that can do that. My T knows that and tries to avoid using them, but I hate calling him just the same (reminds me of my past). So we came up with a plan : I send him a message: I need to see you and he gives me a date the next day, early in the morning (my crisis are at night). Been lucky I guess that he was not asleep.
Only done it twice in 4 years, left it for SU emergencies only.