Hey googley Reading between the lines (an iffy thing I know) it seems like you may feel a little resentment that they don't call you or maybe you think that they would just as soon drop the friendship? If you enjoy talking w/ these friends then I think you should continue the relationships. They could have good reasons. Or reasons that have nothing to do w/ how they value your friendship.
I'm glad you posted this question.
I haven't called any friends in a long time. Two or three are friends that I really like and value. It makes me wonder if they are thinking what you are thinking