Network Documentation is very very important, for Network Admins is a must, because for example a new team member joins, this information will be useful to acknowledge the network infrastructure.
But I'm literally 100% confident given your description, that you are perceiving it as people using "cell phones" to replace VoIP, and not realizing that it's standard VoIP softphones being deployed onto mobile computing devices that are often, but not required to be, cell phones.
We have cisco everything and I was told it was too expensive to have softphones on our cell, we instead must have a separate cell phone. I doubt that, but who knows.
And yet it wasn't too expensive to have Cisco... suspicious.
