We currently have a few servers, around 30-40 workstations and 16 phones. Each device has a static IP address.

As an example the standard settings for a new workstation is;

IP: 192.168.1.XXX
Subnet: 255.255.255.0
Gateway: 192.168.1.99
DNS: 192.168.1.50

As I am slowly exploring new server OS's and virtualisation etc. I am getting close to wanting a wider range of IP addresses.

What I would like to do is seperate the devices by IP as follows:

Servers        192.168.1.XXX
Workstations   192.168.2.XXX
Printers       192.168.3.XXX
Phones         192.168.4.XXX
VM's           192.168.5.XXX

Is this a bad idea, or is this a common way of doing things?

My biggest concern is the phones and subnet masks. The phones are managed by our provider although I have access to the server that runs them.

Would I need to change the subnet mask to 255.255.0.0 on all devices? Or only those that change? For example, the phones don't need to connect to any other devices other than other phones and the phone server. So if I have the phones on 192.168.1.XXX with a subnet mask of 255.255.255.0 and then moved everything I had complete ownership/control of to 192.168.X.XXX with a new subnet mask of 255.255.0.0.

Would that work?