Unfortunately, while "you go and do your phone calls " is good idiomatic English, "I do/am doing a phone call" is not. I think it's because "you go and do X" has become lexicalised to the state where things can take the place of X that do not work that way outside of that particular phrase.
(p.s. in UK English at least, even "I am making a phone call" sounds pretty stilted/formal". To me it would sound more natural to say something like, "I'm ringing someone up" or "I'm on the phone")