In France it is mandatory either with salary or rest. In addition the labor code stipulates mandatory daily rest of 11 contiguous hours even during the weekend and extra 24 contiguous hours of rest during the weekend. Hours of intervention are considered work.

In my company we get approximately 800€ for every week of on-call and each hour of intervention is also compensated with salary.

From my point of view this should be high enough for the company to be willing to focus on on-call issues. Ater years of being on-call I must admit the salary is comfortable but it doesn't cover the pain and constraints of being on-call: being kinda "stuck" at home basically, lots of consequences on private life etc.