When phoning a journalist always think about their deadlines so you don’t ring at the most inappropriate time.
I’ve known journalists to refuse to give some PR agencies the time of day because they’d ring when their radio show was on air or during the news.
For example never ring a journalist in a radio newsroom ten minutes to the hour or during the news at the top of the hour. The best time is just after the news bulletin.
If you want to speak to a producer for a radio or television show wait to ring when the show has finished unless it is a breaking news story.
Print journalists usually get in around 9am and are contactable in the mornings but around 4pm they’re busy with a looming deadline so refrain from ringing then.