How do I know if someone is on their phone when I call

[ladyroyal]

I use to be able to know if someone is on their phone when I call them. Since using S25 ultra it's not working. Is there a way to get this back.

[LongHiker]

@ladyroyal If you get a busy signal, they are on a call. 

[rooney55]

Why would it matter?

[SpeakerUnion]

If they have a voicemail with their voice on it, And it pops up like a normal voicemail, it means they are on the phone with somebody else.

[meself]

If it goes to voicemail they can be on a call or the phone is turned off