i want "phone" feature to open automatically when i hold my n900 in portrait style.
What is the setting for that?

go into phone, go to settings

(1) Open your telephone application by pressing the telephone icon in the main menu;
(2) Once it opens, press the word "phone" at the top of the screen (it will have a blue triangle next to it), this will take you to the phone settings menu;
(3) once the phone settings menu opens, press the button marked "turning control";
(4) press the white box next to the "launch by turning" button, which will cause a check mark to appear, thus selecting that option;
(5) press "save"; and
(6) enjoy.

I'd appreciate your thanks if this helps.