They probably are not true friends, but it would be advantageous to look at it the other way around, just to be sure.
How do you behave? Do you do the same thing? Or do you call them just to stay in touch and to make plans for social engagements. And when you do, what is their response? Do they have excuses for being to busy, or are they interested in pursuing a friendship relationship.
What about your own reaction? Did it ever happen in the past that they did try to reach out to you for purely social reasons, and you were too busy?
When you answer these questions, you’ll have a better feel for the truth. It takes some honest reflection and self-awareness, and it’s worth the exercise.
I’ve experienced both extremes in my life. I had a couple of friends who I determined where toxic to be with, and I decided to let them go. However, I was also able to look inward and realize that I wasn’t paying attention to another friend's needs when it was required. It’s a two-way street, so to say. Hope I’ve helped enlighten you to the big picture.