I use my personal phone. I really do not want a second phone, only down side is once customers and work people have my personal number it can be a bit annoying but not to bad. I was told I can have a work phone, or they offer $ towards my personal. It does not cost me anything more to use it for work bc my plan so I have not asked for anything. Only time it costs me more is if I have to call Germany often, most of the time the costs are not enough to worry about. When I go there I get the $10/day plan added on and submit it in my expense report.
I have had two phones, it had some perks but I found it more annoying than helpful most of the time. I am getting paid decently, using my phone makes my life easier so no need to ask for more for that convenience IMO.