I could use this sentence and say I call my friends on the telephone yo llamo a mis amigos por telefono but if I call myself, which I never do because it never goes through i would need the me that goes after yo and before llamo to make a conjugated or changed verb so if I wanted to say, I call myself just like we already learned, I will say yo me llamo please remember that yo is optional because we already went over that once you have the verb changed 