Apparently this is an EU/US thing, because here overtime and on-call is always paid extra (as is essentially anything beyond your usual 40 hrs/week, or whatever you've got in your contract).
That said, I also see very few jobs that involve on-call. Maybe that's because companies know they have to pay extra for it and therefore don't hand it out willy-nilly, but typically there'll be an ops team who do have on-call, and whose job is to triage and fix anything they can, otherwise just minimise the damage, and then maybe the most business-relevant couple of teams will also have an on-call rotation in case the problem can't be solved by ops alone.
Thats what oncall is, every job ive seen makes you do it