Except that, being a mobile call they can end the call themselves anytime they like.
It used to be the case that – in Britain, anyway – the person receiving a landline call was the one who decided when the call should end, by not putting the receiver down; I was told this ended when companies involved in telesales found that their lines were repeatedly getting blocked by the knowing knowingly not ending calls (but the person who told me this quite often made things up, so…?) and so this facility was dropped.

Flood