Pay for after hours work

I am starting a new IT service division for my company. We will be required to offer 24x7x365 service for our customers. I’m interested in what industry standard is for after hours pay. For the tech that gets an after hours call is it normal to:
1) Pay a % of the after hours premium charged to the customer
2) Offer comp time
3) A combination of both.

Any feedback would be greatly appreciated.