i don't know why this is so baffling to people.
the reason i cannot be contacted by phone is that i don't want you to contact me by phone. some people get excited when somebody wants to talk to them on the phone; i tend to get anxious, and annoyed. i simply do not want to own a device that sits in my house and rings when somebody wants to talk to me; it's an invasion of privacy, and the reality is that if i actually had a phone connected to an actual live service then i'd just turn it off anyways.
i would greatly prefer written communication over verbal communication, and would rather communicate over email than over the phone.
so, i have eliminated means to contact me verbally because i do not like to engage in verbal communication and i find the premise that somebody can ring a bell and expect me to talk to them to be an invasion on my personal privacy that i am not interested in normalizing.