Outgoing calls sometimes go straight to voicemail When I'm trying to call someone, sometimes it'll ring half a time then go straight to voicemail, the other times it'll just keep on ringing for 2 whole minutes before it just cuts off, no voicemail.
These things would be controlled by the person you are calling, not yourself. For example, one could turn on Do Not Disturb (whether manually or by schedule) which would mean your call would go to voicemail if they have that configured.