My mother is mad at me for withholding my brother's telephone number.
When my mom moved into her assisted living facility, I printed (in 48 point type) my home and cell numbers and those for my brother. I encased the page in plastic and put it by her phone.
In the vagaries of memory loss, she is convinced that you can't dial an out-of-town number without telling the operator the city and state you are trying to reach. I explained about area codes, but she didn't believe me. Today, in exasperation, she said, "All telephone numbers start with a word."