My employer provides everyone with an iPhone. Not sure what model mine is, but it's about 6 years old - prepandemic anyway! Maybe 5SE. It could do with replacing actually, it's getting slow and losing battery life. It's provided with a screen protector and bump case. We no longer have desk phones. We are a large gov body, where about 70% of staff have an element of field/peripatetic work, so mobile technology is extremely helpful, not just for keeping in touch and phone calls, but for sending data, photos etc whilst out, dialling into meetings whilst out and accessing documents,looking at risk assessments, maps etc on the fly.
Work pays all business phone costs, keeps the software updated etc. we have the option of using our work phone for personal calls and going through the bill every month and paying for these via a negative expense report. Most people opt not to do this, and just have another personal phone, so they can turn their work phone off when not at work. Also, we're not allowed to take our phones out of the country unless there is a business need.
Work phone use falls under the sane IT use agreement as laptops, desktops and iPads. Ie: basically business use only, and they are monitored!
Both my personal and work phones are set up to receive business continuity messages, so I don't miss news about my office being closed (again!)!
Obvs my line manager can access my personal contact details if needed.