Texts: I can text her, but there's no point. She rarely checks them.
Phone: I call her when in a crisis or when I need reassurance/a check-in. We maybe talk on the phone once a month? It really just depends. I think the most was twice in one week.
Email: I email my T anywhere from 1 to 5 times a week. Usually, it's twice. I can email for any reason. There are "suggested" boundaries: 2 emails a week, no novels, sleep on it before sending it, no cat pictures (yes, my T hates cats that much), and no crisis emails. I haven't always adhered to those "suggestions"...except the no cats one. I do usually stay within those limits. It used to be a firm boundary, but I asked her to remove it and to trust me. She says I'm doing fine regulating my emails

Oh, and I am never supposed to expect a reply. Usually her reply is "Don't worry. We will talk about it on Tuesday".
For scheduling: it's either phone or email.
Most of our out-of-session contact is through emails. I can reach out at any time, but she might not respond. She does tell me when she will be unavailable to respond if she goes on vacation or something. I need to know this because contacting her is part of my crisis plan. If I'm in a crisis, I'm supposed to contact her. I am not allowed to act on any of my thoughts until I hear back from her.
Sometimes she will initiate contact. It could be to check-in, scheduling, update with insurance or Pdoc. This Thursday she will actually email me just to provide me with extra reassurance because I'm struggling so much.