How do you get people to stop assuming your landline is a mobile phone?

[hlthe2b]

4. That the landline doesn't send a signal to the cell phone clearly blocking the attempt is

frustrating as I have tried to contact people with only a "phone number" listed and I have no way of knowing it is a landline. If I don't get an answer and there is no voice mail option, I hang up to try to send a text. I never send confidential patient information, given I have no way of knowing if the phone number is valid, but I'd still like to convey that I tried to reach them. I guess there is no impetus to try to streamline interphases between high and lower technology.