My mom used to call me 2-3 times a week at work. And sometimes it bothered me, too. I work in a cube and people can overhear my conversations. Mom was hard of hearing, so there was some loud talking going on at my end, so she could hear me. But we all dealt with it; my co-workers have parents, too, and we all understand.
Mom died last November. What I wouldn't give to have that phone ring now. Her phone calls are something that I really miss.
Since my mother passed away, though, my MIL started to call me....about once a week. Just to talk. I always pick up the phone when I see it's her. Life is too short to complain about the small stuff.