I've used texting for scheduling, calling rarely because calls to me are a rather personal zone I don't want therapists in, and emails other than specifically online therapists, we've exchanged rarely.
I'm good communicating over email, therapists I was with were rather busy or not using that modality in their practice very much.
As to crises, my therapists & me had a wildly differing idea what 'crisis' is, or how to behave in it. The last people I'm likely to hit up in a crisis are authorities of any kind, unless I'm working with them. And when in crisis, I don't need soothing / comfort of the sympathy kind, I need someone to restart my ability to think & trust my thoughts & act on them.