My daughter is a college student. She has a smart phone, which she carries with her all the time, but keeps in her purse. The purse is often (allegedly) left in the car, in a bedroom, under the table, or someplace else inaccessible, so she does not always answer it (at least when one or the other parents call). (I believe that, oh, yes I do. I also believe in Santa Clause and the Tooth Fairy.) She is generally available only by email or text message. Occasionally she answers the phone, mainly in order to throw me off. The key thing is that, while I can rarely actually talk to her when I want to, I can always leave a message in one of several ways, and she can tell how many times I tried to reach out to her.
When my mother lived in her own home, she had a portable phone with caller ID. She was usually home, but if she was out or on the phone, she could always tell when I called, so she, too, knew when I was thinking of her. Sometimes she would even remember to turn on the damned answering machine so I could leave an actual voice message. (Not very often, but sometimes.)
My mother is now in a convalescent center where she is undergoing rehabilitation therapy. There are only certain hours of the day when she is in her room. She has a basic phone in her room, with no answering service and no caller ID. I spoke to her on Monday for a while, after trying several times and getting a busy signal (I hadn't heard a busy signal in so long, I thought there was something wrong with my phone). Tuesday she had company when I called, so we spoke for only a minute. Today I have tried five times to reach her and the line has been busy every time. Now it is too late to call because it's almost her bedtime!
Lord, I may have to actually resort to writing letters and mailing them.... then again, maybe I'll try calling her early in the morning when I'm on my way to work! That's worth a try, anyway.
Anything to avoid printing out an actual letter and having to buy a postage stamp! What does a stamp cost these days, anyway?