Yes, you can. Theres no problem with that. But you have to consider the following. If you use DNS you have to update your DNS server in order to register the changes you make. And if you change your call manager Hostname to IP Address you need to change it manually. Then if you also modify some parameters on the Call Manager service parameters (using IP address of the call manager instead of using the hostname) you need to change it also. In short you must change all parameters that are using IP Address of your call manager.
have fun...
