It depends on the company, however, most want you to have an old fashioned land line for security and reliability reasons. Drop calls are a lot more frequent with Voip which can cause a lot of angry customers and companies losing money.
A line through your internet provider is not usually VOIP. If it’s through your cable company, it is just fine for job purposes. I’m not sure if it’s the same for a satellite internet provider, but if it’s cable or DSL, those are fine.
My phone is through our internet provider. It’s not cable, more like satellite, and the line drops sometimes or goes offline. It’s frustrating when you are trying to reach someone and the line goes dead. I wouldn’t suggest using anything but an old fashion land line.
I worked a home call center job for awhile, and they definitely wanted me to have an old fashioned land line. It certainly would have been more convenient the other way, since I already had an internet provider phone line, but they wouldn’t go for it.
In the current state of the art, old-school landlines are still far more reliable than any other type of connection. I use landline for phone jobs, and a cell for business calls outside of the phone jobs. For me, internet-based calling is reserved for conference calls.
On a household safety note, I find it reassuring to have all 3 communications options available, because it’s rare to have all of them fail at once.
It seems like almost every company wants a different type of phone setup. Right now we have something called a hybrid. It is not a full VOIP line, it is not traditional, but it is digital. I don’t understand it at all.