I agree with other TAs feedback that many of us here try to be as 24/7 or accessible as possible by default already...However, I have recently had a VIP client who travels often, with a very dynamic schedule and insisted to pay an annual fee to ensure I'm reachable to him at all times, true 24/7. He also doesn't want to speak with anyone at my agency or air desk, has to be me. So, I'd have to basically plan all my own travels or anything around his bookings so I know I'm not out of reach if he is on a trip. He is on my iPhone's important contact list (so night mode doesn't block his calls) which only my mom and wife were previously on, LOL! That's a whole different level of accessibility...But we make it work.