Mindfulness is great, but in my case I noticed that the usual techniques don't work. I needed to find my own techniques. For instance most autistics have some kind of special interest. Diving into that certainly helps me. It's where my mind can roam freely.
Calling is OK for me.. Getting called now? That's hell. Totally no control over sensory input (that infernal ringing noise), no control over who or when or what they want?