Should I get a phone just for work? Or my personal phone is enough?

I'm an operations manager and my work require 24 hours line. I don't see a point from seperating but thats what people do…
Any alternatives to gettig two phones? I currently have an iphone

Buy a dual sim android handset.

http://www.techadvisor.co.uk/test-centre/mobile-phone/best-dual-sim-phones-for-2017-3511526/

The dual-SIM phone is an option. You get 2 numbers in the same device, and you know which number is being called prior to answering. Large number of models available, but you'll have to ask specifically for a dual-SIM version in most cases.

A second cheap phone using a second cheap service is also an option. If all you need is calls, any cheap $19 Tracphone will work. If you need calls and texts, you may need to look at another carrier like AT&T's GoPhone (or whatever they call it now) or SimpleMobile or Virgin or the like. If you require full smartphone capability, you can still get a cheap Android and service.

Or, you can try and get the company to pay for your phone. They require it, make them furnish it. My workplace requires that I have their phone on my person basically 24/7, but they provide that phone. I do work stuff on my work phone, and I do personal stuff on my personal phone.

If your work is requiring you to have a phone and be available 24/7, then they should either provide a phone or pay at least a portion of your phone bill. My current employer provides me with a phone, my previous employer required me to use my own phone, but gave me a monthly phone stipend to help pay for part of the cost. I wish I had known about this dual SIM option when I was using my personal phone, that sounds like a fascinating option.