It is a net perk because phone calling or mobile messaging is inevitably part of work and you don't want to buy your own separate phone. It's only awkward for anyone who isn't used to having two phones.
Calling and messaging are paid for by my company, and I can also sign in to my email. They have a program where I can get full access to all work resources, but it’s optional, and I will never sign up for that program, because exactly what’s being discussed here. But I still only have one phone, and they still pay for it, so.
Is the contract in your name and you pay the bill yourself and then expense it? Or is the contract in company's name they get full itemized bill from the carrier? If it is the latter, it sucks.
They get the bill directly, but I'm not sure they can have access to the messaging or call data directly. I live in Europe, so I feel like the GDPR addresses this, but now that you mention it, I don't know this for sure.