No, "ringer" by itself means "ring(s)/is ringing" like making a sound. "Klokken ringer" - the bell rings, and "telefonen ringer" - the telephone is ringing, are examples. This has nothing at all to do with "kalder på", to answer your question :)
To be really thorough, there is another way of using "ringer/at ringe" when including the word "med". I answered that one a few days ago. https://www.duolingo.com/comment/7683766 -here you go :) I hope it's helpful and that I didn't just make everything even more confusing!
Just checking - Can I assume that "ringer" only means "call" in the sense of phoning someone, and not (say) calling your children who are some distance away?