What's the difference between call and call up to mean make a telephone call to? Is the latter any more informal than the former, or is it mainly a regional thing?
call someone or something up
To telephone someone or something: As soon as I heard the news, I called up my broker and told her to sell the stock. I called him up to ask if he was free for lunch.
call someone up
(especially North American English) to make a telephone call to someone
call (someone) up or call up (someone)
chiefly US : to make a telephone call to (someone)
I haven't spoken to her in years, but I called her up last night and we talked for hours.
Call me up when you get back from your vacation.
I called up my doctor and made an appointment.