How should I respond when I feel like I am talking to a wall?

This only happens on the phone and unfortunately I have to talk on the phone with my husband a lot because he is in the military and we are separated sometimes for months at a time. I love him to pieces and I know he is a quiet guy and I have absolutely no problem with that. However, I hate talking on the phone as it is because it makes me feel how far we are from each other, but then to have this problems only makes things worse. It’s not an actual problem in our relationship but it does drive me crazy. I just don’t know how to react when I tell him about my day and I don’t even get so much as a grunt. I know I am not saying anything very important most of the time but I just feel like I am talking to myself when he is on the phone. In person it doesn’t bother me. In person we talk all night long and don’t even realize until the sun comes up.

I try not to get mad but I do. How am I supposed to react to this? I am trying to have some positive self talk but I have run out of positive.