I know somebody who does this and accidentally racked up a £3,500 phone bill while on holiday. He was accidentally using the wrong SIM for data.

I have two phones. A personal one and one provided by my company. I like being able to turn off my work phone when on holiday, etc and keep my personal life separate.

I do know a lot of people who sold their personal phones when given a work phone and use it for both. Saves some money I guess but no thanks.

I also know people who have two phones but install all the work apps on their personal phones to make it easier for them. No thanks!