present perfect progressive?

Hello

I have tried to ring you several times today. Where have you been?
I have been calling you for half an hour. where have you been?

the second sentence insists on the duration ok for present perfect progressive but for me the first sentence too because of "several" so why present perfect simple?
In both cases I have found the person to talk too so I don't ring or call anymore.So why is there a difference and what means this difference?
Is it a question of continuity " I have been calling" means in that period I have only been doing calling?I have tried means I have done some pause
between the calls?

Thanks for your answer