What's your on-call rotation like? How often are you on/off and how many people are in the rotation? Do you get called a ton or seldom ever called? What are you supporting after hours? Any horror stories?
Just curious after some on-call annoyance myself

Current position (<3 months):
Industry: health provider
Company size: 6500 employees
Size of IT Dept: ~650
On-Call: One week on, 4 weeks off
Rotation members: 5
Supporting: ~500 servers
How terrible: This is my first go-around of on-call. So far I am a few days in and have been called once for something pretty trivial. It also means I get dumped with after-hours support and undesirable changes, so I've already got a 5AM scheduled change Sunday morning. I was also just given 10 hrs notice (surprise!) that I'll be supporting a 6-hour change TONIGHT. So much for my plans

Last position:
Industry: Casino/Resort
Company size: 5000 employees
Size of IT Dept: 100
On-Call: Two weeks on, two weeks off
Rotation members: 2
Supporting: 65 production servers, including the revenue generating core of the business
How terrible: Called maybe 5 times in 1.5 years. Never anything crazy and often issues that could wait overnight or over the weekend.
First job:
Industry: Aerospace/defense
Company size: 250,000 employees
Size of IT Dept: massive.
On-call: 1 week on, 5 weeks off
Rotation members: 6
Supporting: 400 servers
How terrible: Expected to be called multiple times every on-call. Global organization so people are still on "business hours" while you're sleeping. Several 8+ hours conference calls to address issues. Really really not worth it.